The Mark of Athena

Leo felt more like a ghost than ever. Maybe he had actually been an eidolon his whole life, because this kid he’d just seen should have been the real Leo. He was smarter, cooler, and funnier. He flirted so well with Hazel that he had obviously stolen her heart.

No wonder Hazel had looked at Leo so strangely when they first met. No wonder she had said Sammy with so much feeling. But Leo wasn’t Sammy, any more than Flathead Rufus was Clark Gable.

“Hazel,” he said. “I—I don’t—”

The schoolyard dissolved into a different scene.

Hazel and Leo were still ghosts, but now they stood in front of a rundown house next to a drainage ditch overgrown with weeds. A clump of banana trees drooped in the yard. Perched on the steps, an old-fashioned radio played conjunto music, and on the shaded porch, sitting in a rocking chair, a skinny old man gazed at the horizon.

“Where are we?” Hazel asked. She was still only vapor, but her voice was full of alarm. “This isn’t from my life!”

Leo felt as if his ghostly self was thickening, becoming more real. This place seemed strangely familiar.

“It’s Houston,” he realized. “I know this view. That drainage ditch…This is my mom’s old neighborhood, where she grew up. Hobby Airport is over that way.”

“This is your life?” Hazel said. “I don’t understand! How—?”

“You’re asking me?” Leo demanded.

Suddenly the old man murmured, “Ah, Hazel…”

A shock went up Leo’s spine. The old man’s eyes were still fixed on the horizon. How did he know they were here?

“I guess we ran out of time,” the old man continued dreamily. “Well…”

He didn’t finish the thought.

Hazel and Leo stayed very still. The old man made no further sign that he saw them or heard them. It dawned on Leo that the guy had been talking to himself. But then why had he said Hazel’s name?

He had leathery skin, curly white hair, and gnarled hands, like he’d spent a lifetime working in a machine shop. He wore a pale yellow shirt, spotless and clean, with gray slacks and suspenders and polished black shoes.

Despite his age, his eyes were sharp and clear. He sat with a kind of quiet dignity. He looked at peace—amused, even, like he was thinking, Dang, I lived this long? Cool!

Leo was pretty sure he had never seen this man before. So why did he seem familiar? Then he realized the man was tapping his fingers on the arm of his chair, but the tapping wasn’t random. He was using Morse code, just like Leo’s mother used to do with him…and the old man was tapping the same message: I love you.

The screen door opened. A young woman came out. She wore jeans and a turquoise blouse. Her hair was cut in a short black wedge. She was pretty, but not delicate. She had well-muscled arms and calloused hands. Like the old man’s, her brown eyes glinted with amusement. In her arms was a baby, wrapped in a blue blanket.

“Look, mijo,” she said to the baby. “This is your bisabuelo. Bisabuelo, you want to hold him?”

When Leo heard her voice, he sobbed.

It was his mother—younger than he remembered her, but very much alive. That meant the baby in her arms…

The old man broke into a huge grin. He had perfect teeth, as white as his hair. His face crinkled with smile lines. “A boy! Mi bebito, Leo!”

“Leo?” Hazel whispered. “That—that’s you? What is bisabuelo?”

Leo couldn’t find his voice. Great-grandfather, he wanted to say.

The old man took baby Leo in his arms, chuckling with appreciation and tickling the baby’s chin—and Ghost Leo finally realized what he was seeing.

Somehow, Hazel’s power to revisit the past had found the one event that connected both of their lives—where Leo’s time line touched Hazel’s.

This old man…

“Oh…” Hazel seemed to realize who he was at the same moment. Her voice became very small, on the verge of tears. “Oh, Sammy, no…”

“Ah, little Leo,” said Sammy Valdez, aged well into his seventies. “You’ll have to be my stunt double, eh? That’s what they call it, I think. Tell her for me. I hoped I would be alive, but, ay, the curse won’t have it!”

Hazel sobbed. “Gaea…Gaea told me that he died of a heart attack, in the 1960s. But this isn’t—this can’t be…”

Sammy Valdez kept talking to the baby, while Leo’s mother, Esperanza, looked on with a pained smile—perhaps a little worried that Leo’s bisabuelo was rambling, a little sad that he was speaking nonsense.

“That lady, Doña Callida, she warned me.” Sammy shook his head sadly. “She said Hazel’s great danger would not happen in my lifetime. But I promised I would be there for her. You will have to tell her I’m sorry, Leo. Help her if you can.”

“Bisabeulo,” Esperanza said, “you must be tired.”

She extended her arms to take the baby, but the old man cuddled him a moment longer. Baby Leo seemed perfectly fine with it.

“Tell her I’m sorry I sold the diamond, eh?” Sammy said. “I broke my promise. When she disappeared in Alaska…ah, so long ago, I finally used that diamond, moved to Texas as I always dreamed. I started my machine shop. Started my family! It was a good life, but Hazel was right. The diamond came with a curse. I never saw her again.”

“Oh, Sammy,” Hazel said. “No, a curse didn’t keep me away. I wanted to come back. I died!”

The old man didn’t seem to hear. He smiled down at the baby, and kissed him on the head. “I give you my blessing, Leo. First male great-grandchild! I have a feeling you are special, like Hazel was. You are more than a regular baby, eh? You will carry on for me. You will see her someday. Tell her hello for me.”

“Bisabuelo,” Esperanza said, a little more insistently.

“Yes, yes.” Sammy chuckled. “El viejo loco rambles on. I am tired, Esperanza. You are right. But I’ll rest soon. It’s been a good life. Raise him well, nieta.”

The scene faded.

Leo was standing on the deck of the Argo II, holding Hazel’s hand. The sun had gone down, and the ship was lit only by bronze lanterns. Hazel’s eyes were puffy from crying.

What they’d seen was too much. The whole ocean heaved under them, and now for the first time Leo felt as if they were totally adrift.

“Hello, Hazel Levesque,” he said, his voice gravelly.

Her chin trembled. She turned away and opened her mouth to speak, but before she could, the ship lurched to one side.

“Leo!” Coach Hedge yelled.

Festus whirred in alarm and blew flames into the night sky. The ship’s bell rang.

“Those monsters you were worried about?” Hedge shouted. “One of ’em found us!”

LEO DESERVED A DUNCE CAP.

If he’d been thinking straight, he would’ve switched the ship’s detection system from radar to sonar as soon as they left Charleston Harbor. That’s what he had forgotten. He’d designed the hull to resonate every few seconds, sending waves through the Mist and alerting Festus to any nearby monsters, but it only worked in one mode at a time: water or air.

He’d been so rattled by the Romans, then the storm, then Hazel, that he had completely forgotten. Now, a monster was right underneath them.

The ship tilted to starboard. Hazel gripped the rigging. Hedge yelled, “Valdez, which button blows up monsters? Take the helm!”

Leo climbed the tilting deck and managed to grab the port rail. He started clambering sideways toward the helm, but when he saw the monster surface, he forgot how to move.

The thing was the length of their ship. In the moonlight, it looked like a cross between a giant shrimp and a cockroach, with a pink chitinous shell, a flat crayfish tail, and millipede-type legs undulating hypnotically as the monster scraped against the hull of the Argo II.

Its head surfaced last—the slimy pink face of an enormous catfish with glassy dead eyes, a gaping toothless maw, and a forest of tentacles sprouting from each nostril, making the bushiest nose beard Leo had ever had the displeasure to behold.

Leo remembered special Friday night dinners he and his mom used to share at a local seafood restaurant in Houston. They would eat shrimp and catfish. The idea now made him want to throw up.

“Come on, Valdez!” Hedge yelled. “Take the wheel so I can get my baseball bat!”

“A bat’s not going to help,” Leo said, but he made his way toward the helm.

Behind him, the rest of his friends stumbled up the stairs.

Percy yelled, “What’s going— Gah! Shrimpzilla!”

Frank ran to Hazel’s side. She was clutching the rigging, still dazed from her flashback, but she gestured that she was all right.

The monster rammed the ship again. The hull groaned. Annabeth, Piper, and Jason tumbled to starboard and almost rolled overboard.

Leo reached the helm. His hands flew across the controls. Over the intercom, Festus clacked and clicked about leaks belowdecks, but the ship didn’t seem to be in danger of sinking—at least not yet.

Leo toggled the oars. They could convert into spears, which should be enough to drive the creature away. Unfortunately, they were jammed. Shrimpzilla must have knocked them out of alignment, and the monster was in spitting distance, which meant that Leo couldn’t use the ballistae without setting the Argo II on fire as well.

“How did it get so close?” Annabeth shouted, pulling herself up on one of the rail shields.

“I don’t know!” Hedge snarled. He looked around for his bat, which had rolled across the quarterdeck.

“I’m stupid!” Leo scolded himself. “Stupid, stupid! I forgot the sonar!”

The ship tilted farther to starboard. Either the monster was trying to give them a hug, or it was about to capsize them.

“Sonar?” Hedge demanded. “Pan’s pipes, Valdez! Maybe if you hadn’t been staring into Hazel’s eyes, holding hands for so long—”

“What?” Frank yelped.

“It wasn’t like that!” Hazel protested.

“It doesn’t matter!” Piper said. “Jason, can you call some lightning?”

Jason struggled to his feet. “I—” He only managed to shake his head. Summoning the storm earlier had taken too much out of him. Leo doubted the poor guy could pop a spark plug in the shape he was in.

“Percy!” Annabeth said. “Can you talk to that thing? Do you know what it is?”

The son of the sea god shook his head, clearly mystified. “Maybe it’s just curious about the ship. Maybe—”

The monster’s tendrils lashed across the deck so fast, Leo didn’t even have time to yell, Look out!

One slammed Percy in the chest and sent him crashing down the steps. Another wrapped around Piper’s legs and dragged her, screaming, toward the rail. Dozens more tendrils curled around the masts, encircling the crossbows and ripping down the rigging.

“Nose-hair attack!” Hedge snatched up his bat and leaped into action; but his hits just bounced harmlessly off the tendrils.

Jason drew his sword. He tried to free Piper, but he was still weak. His gold blade cut through the tendrils with no problem, but faster than he could sever them, more took their place.

Annabeth unsheathed her dagger. She ran through the forest of tentacles, dodging and stabbing at whatever target she could find. Frank pulled out his bow. He fired over the side at the creature’s body, lodging arrows in the chinks of its shell; but that only seemed to annoy the monster. It bellowed, and rocked the ship. The mast creaked like it might snap off.

They needed more firepower, but they couldn’t use ballistae. They needed to deliver a blast that wouldn’t destroy the ship. But how… ?

Leo’s eyes fixed on a supply crate next to Hazel’s feet.

“Hazel!” he yelled. “That box! Open it!”

She hesitated, then saw the box he meant. The label read WARNING. DO NOT OPEN.

“Open it!” Leo yelled again. “Coach, take the wheel! Turn us toward the monster, or we’ll capsize.”

Hedge danced through the tentacles with his nimble goat hooves, smashing away with gusto. He bounded toward the helm and took the controls.

“Hope you got a plan!” he shouted.

“A bad one.” Leo raced toward the mast.

The monster pushed against the Argo II. The deck lurched to forty-five degrees. Despite everyone’s efforts, the tentacles were just too numerous to fight. They seemed able to elongate as much as they wanted. Soon they’d have the Argo II completely entangled. Percy hadn’t appeared from below. The others were fighting for their lives against nose hair.

“Frank!” Leo called as he ran toward Hazel. “Buy us some time! Can you turn into a shark or something?”

Frank glanced over, scowling; and in that moment a tentacle slammed into the big guy, knocking him overboard.

Hazel screamed. She’d opened the supply box and almost dropped the two glass vials she was holding.

Leo caught them. Each was the size of an apple, and the liquid inside glowed poisonous green. The glass was warm to the touch. Leo’s chest felt like it might implode from guilt. He’d just distracted Frank and possibly gotten him killed, but he couldn’t think about it. He had to save the ship.

“Come on!” He handed Hazel one of the vials. “We can kill the monster—and save Frank!”

He hoped he wasn’t lying. Getting to the port rail was more like rock climbing than walking, but finally they made it.

“What is this stuff?” Hazel gasped, cradling her glass vial.

“Greek fire!”

Her eyes widened. “Are you crazy? If these break, we’ll burn the whole ship!”

“Its mouth!” Leo said. “Just chuck it down its—”

Suddenly Leo was crushed against Hazel, and the world turned sideways. As they were lifted into the air, he realized they’d been wrapped together in a tentacle. Leo’s arms were free, but it was all he could do to keep hold of his Greek fire vial. Hazel struggled. Her arms were pinned, which meant at any moment the vial trapped between them might break…and that would be extremely bad for their health.

They rose ten feet, twenty feet, thirty feet above the monster. Leo caught a glimpse of his friends in a losing battle, yelling and slashing at the monster’s nose hairs. He saw Coach Hedge struggling to keep the ship from capsizing. The sea was dark, but in the moonlight he thought he saw a glistening object floating near the monster—maybe the unconscious body of Frank Zhang.

“Leo,” Hazel gasped, “I can’t—my arms—”

“Hazel,” he said. “Do you trust me?”

“No!”

“Me neither,” Leo admitted. “When this thing drops us, hold your breath. Whatever you do, try to chuck your vial as far away from the ship as possible.”

“Why—why would it drop us?”

Leo stared down at the monster’s head. This would be a tough shot, but he had no choice. He raised the vial in his left hand. He pressed his right hand against the tentacle and summoned fire to his palm—a narrowly focused, white-hot burst.

That got the creature’s attention. A tremble went all the way down the tentacle as its flesh blistered under Leo’s touch. The monster raised its maw, bellowing in pain, and Leo threw his Greek fire straight down its throat.

After that, things got fuzzy. Leo felt the tentacle release them. They fell. He heard a muffled explosion and saw a green flash of light inside the giant pink lampshade of the monster’s body. The water hit Leo’s face like a brick wrapped in sandpaper, and he sank into darkness. He clamped his mouth shut, trying not to breathe, but he could feel himself losing consciousness.

Through the sting of the salt water, he thought he saw the hazy silhouette of the ship’s hull above—a dark oval surrounded by a green fiery corona, but he couldn’t tell if the ship was actually on fire.

Killed by a giant shrimp, Leo thought bitterly. At least let the Argo II survive. Let my friends be okay.

His vision began to dim. His lungs burned.

Just as he was about to give up, a strange face hovered over him—a man who looked like Chiron, their trainer back at Camp Half-Blood. He had the same curly hair, shaggy beard, and intelligent eyes—a look somewhere between wild hippie and fatherly professor, except this man’s skin was the color of a lima bean. The man silently held up a dagger. His expression was grim and reproachful, as if to say: Now, hold still, or I can’t kill you properly.

Leo blacked out.

When Leo woke, he wondered if he was a ghost in another flashback, because he was floating weightlessly. His eyes slowly adjusted to the dim light.

“About time.” Frank’s voice had too much reverb, like he was speaking through several layers of plastic wrap.

Leo sat up…or rather he drifted upright. He was underwater, in a cave about the size of a two-car garage. Phosphorescent moss covered the ceiling, bathing the room in a blue-and-green glow. The floor was a carpet of sea urchins, which would have been uncomfortable to walk on, so Leo was glad he was floating. He didn’t understand how he could be breathing with no air.

Frank levitated nearby in meditation position. With his chubby face and his grumpy expression, he looked like a Buddha who’d achieved enlightenment and wasn’t thrilled about it.

The only exit to the cave was blocked by a massive abalone shell—its surface glistening in pearl and rose and turquoise. If this cave was a prison, at least it had an awesome door.

“Where are we?” Leo asked. “Where is everyone else?”

“Everyone?” Frank grumbled. “I don’t know. As far as I can tell, it’s just you and me and Hazel down here. The fish-horse guys took Hazel about an hour ago, leaving me with you.”

Frank’s tone made it obvious he didn’t approve of those arrangements. He didn’t look injured, but Leo realized that he no longer had his bow or quiver. In a panic, Leo patted his waist. His tool belt was gone.

“They searched us,” Frank said. “Took anything that could be a weapon.”

“Who?” Leo demanded. “Who are these fish-horse—?”

“Fish-horse guys,” Frank clarified, which wasn’t very clear. “They must have grabbed us when we fell in the ocean and dragged us…wherever this is.”

Leo remembered the last thing he’d seen before he passed out—the lima-bean-colored face of the bearded man with the dagger. “The shrimp monster. The Argo II—is the ship okay?”

“I don’t know,” Frank said darkly. “The others might be in trouble or hurt, or—or worse. But I guess you care more about your ship than your friends.”

Leo felt like his face had just hit the water again. “What kind of stupid thing—?”

Then he realized why Frank was so angry: the flashback. Things had happened so fast with the monster attack, Leo had almost forgotten. Coach Hedge had made that stupid comment about Leo and Hazel holding hands and gazing into each other’s eyes. It probably hadn’t helped that Leo had gotten Frank knocked overboard right after that.

Suddenly Leo found it hard to meet Frank’s gaze.

“Look, man…I’m sorry I got us into this mess. I totally jacked things up.” He took a deep breath, which felt surprisingly normal, considering he was underwater. “Me and Hazel holding hands…it’s not what you think. She was showing me this flashback from her past, trying to figure out my connection with Sammy.”

Frank’s angry expression started to unknot, replaced by curiosity. “Did she…did you figure it out?”

“Yeah,” Leo said. “Well, sort of. We didn’t get a chance to talk about it afterward because of Shrimpzilla, but Sammy was my great-grandfather.”

He told Frank what they’d seen. The weirdness hadn’t fully registered yet, but now, trying to explain it aloud, Leo could hardly believe it. Hazel had been sweet on his bisabuelo, a guy who had died when Leo was a baby. Leo hadn’t made the connection before, but he had a vague memory of older family members calling his grandfather Sam Junior. Which meant Sam Senior was Sammy, Leo’s bisabuelo. At some point, Tía Callida—Hera herself—had talked with Sammy, consoling him and giving him a glimpse into the future, which meant that Hera had been shaping Leo’s life generations before he was even born. If Hazel had stayed in the 1940s, if she’d married Sammy, Leo might’ve been her great-grandson.

“Oh, man,” Leo said when he had finished the story. “I don’t feel so good. But I swear on the Styx, that’s what we saw.”

Frank had the same expression as the monster catfish head—wide glassy eyes and an open mouth. “Hazel…Hazel liked your great-grandfather? That’s why she likes you?”

“Frank, I know this is weird. Believe me. But I don’t like Hazel—not that way. I’m not moving in on your girl.”

Frank knit his eyebrows. “No?”

Leo hoped he wasn’t blushing. Truthfully, he had no idea how he felt about Hazel. She was awesome and cute, and Leo had a weakness for awesome cute girls. But the flashback had complicated his feelings a lot.

Besides, his ship was in trouble.

I guess you care more about your ship than your friends, Frank had said.

That wasn’t true, was it? Leo’s dad, Hephaestus, had admitted once that he wasn’t good with organic life forms. And, yes, Leo had always been more comfortable with machines than people. But he did care about his friends. Piper and Jason…he’d known them the longest, but the others were important to him too. Even Frank. They were like family.

The problem was, it had been so long since Leo had had a family, he couldn’t even remember how it felt. Sure, last winter he’d become senior counselor of Hephaestus cabin; but most of his time had been spent building the ship. He liked his cabin mates. He knew how to work with them—but did he really know them?

If Leo had a family, it was the demigods on the Argo II—and maybe Coach Hedge, which Leo would never admit aloud.

You will always be the outsider, warned Nemesis’s voice; but Leo tried to push that thought aside.

“Right, so…” He looked around him. “We need to make a plan. How are we breathing? If we’re under the ocean, shouldn’t we be crushed by the water pressure?”

Frank shrugged. “Fish-horse magic, I guess. I remember the green guy touching my head with the point of a dagger. Then I could breathe.”

Leo studied the abalone door. “Can you bust us out? Turn into a hammerhead shark or something?”

Frank shook his head glumly. “My shape-shifting doesn’t work. I don’t know why. Maybe they cursed me, or maybe I’m too messed up to focus.”

“Hazel could be in trouble,” Leo said. “We’ve got to get out of here.”

He swam to the door and ran his fingers along the abalone. He couldn’t feel any kind of latch or other mechanism. Either the door could only be opened by magic or sheer force was required—neither of which was Leo’s specialty.

“I’ve already tried,” Frank said. “Even if we get out, we have no weapons.”

“Hmm…” Leo held up his hand. “I wonder.”

He concentrated, and fire flickered over his fingers. For a split second, Leo was excited, because he hadn’t expected it to work underwater. Then his plan started working a little too well. Fire raced up his arm and over his body until he was completely shrouded in a thin veil of flame. He tried to breathe, but he was inhaling pure heat.

“Leo!” Frank flailed backward like he was falling off a bar stool. Instead of racing to Leo’s aid, he hugged the wall to get as far away as possible.

Leo forced himself to stay calm. He understood what was going on. The fire itself couldn’t hurt him. He willed the flames to die and counted to five. He took a shallow breath. He had oxygen again.

Frank stopped trying to merge with the cave wall. “You’re…you’re okay?”

“Yeah,” Leo grumbled. “Thanks for the assist.”

“I—I’m sorry.” Frank looked so horrified and ashamed it was hard for Leo to stay mad at him. “I just…what happened?”

“Clever magic,” Leo said. “There’s a thin layer of oxygen around us, like an extra skin. Must be self-regenerating. That’s how we’re breathing and staying dry. The oxygen gave the fire fuel—except the fire also suffocated me.”

“I really don’t…” Frank gulped. “I don’t like that fire summoning you do.” He started getting cozy with the wall again.

Leo didn’t mean to, but he couldn’t help laughing. “Man, I’m not going to attack you.”

“Fire,” Frank repeated, like that one word explained everything.

Leo remembered what Hazel had said—that his fire made Frank nervous. He’d seen the discomfort in Frank’s face before, but Leo hadn’t taken it seriously. Frank seemed way more powerful and scary than Leo was.

Now it occurred to him that Frank might have had a bad experience with fire. Leo’s own mom had died in a machine shop blaze. Leo had been blamed for it. He’d grown up being called a freak, an arsonist, because whenever he got angry, things burned.

“Sorry I laughed,” he said, and he meant it. “My mom died in a fire. I understand being afraid of it. Did, uh…did something like that happen with you?”

Frank seemed to be weighing how much to say. “My house…my grandmother’s place. It burned down. But it’s more than that…” He stared at the sea urchins on the floor. “Annabeth said I could trust the crew. Even you.”

“Even me, huh?” Leo wondered how that had come up in conversation. “Wow, high praise.”

“My weakness…” Frank started, like the words cut his mouth. “There’s this piece of firewood—”

The abalone door rolled open.

Leo turned and found himself face-to-face with Lima Bean Man, who wasn’t actually a man at all. Now that Leo could see him clearly, the guy was by far the weirdest creature he’d ever met, and that was saying a lot.

From the waist up, he was more or less human—a thin, bare-chested dude with a dagger in his belt and a band of seashells strapped across his chest like a bandolier. His skin was green, his beard scraggly brown, and his longish hair was tied back in a seaweed bandana. A pair of lobster claws stuck up from his head like horns, turning and snapping at random.

Leo decided he didn’t look so much like Chiron. He looked more like the poster Leo’s mom used to keep in her workspace—that old Mexican bandit Pancho Villa, except with seashells and lobster horns.

From the waist down, the guy was more complicated. He had the forelegs of a blue-green horse, sort of like a centaur, but toward the back, his horse body morphed into a long fishy tail about ten feet long, with a rainbow-colored, V-shaped tail fin.

Now Leo understood what Frank meant about fish-horse guys.

“I am Bythos,” said the green man. “I will interrogate Frank Zhang.”

His voice was calm and firm, leaving no room for debate.

“Why did you capture us?” Leo demanded. “Where’s Hazel?”

Bythos narrowed his eyes. His expression seemed to say: Did this tiny creature just talk to me? “You, Leo Valdez, will go with my brother.”

“Your brother?”

Leo realized that a much larger figure was looming behind Bythos, with a shadow so wide, it filled the entire cave entrance.

“Yes,” Bythos said with a dry smile. “Try not to make Aphros mad.”

APHROS LOOKED LIKE HIS BROTHER, except he was blue instead of green and much, much bigger. He had Arnold-as-Terminator abs and arms, and a square, brutish head. A huge Conan-approved sword was strapped across his back. Even his hair was bigger—a massive globe of blue-black frizz so thick that his lobster-claw horns appeared to be drowning as they tried to swim their way to the surface.

“Is that why they named you Aphros?” Leo asked as they glided down the path from the cave. “Because of the Afro?”

Aphros scowled. “What do you mean?”

“Nothing,” Leo said quickly. At least he would never have trouble remembering which fish dude was which. “So what are you guys, exactly?”

“Ichthyocentaurs,” Aphros said, like it was a question he was tired of answering.

“Uh, icky what?”

“Fish centaurs. We are the half brothers of Chiron.”

“Oh, he’s a friend of mine!”

Aphros narrowed his eyes. “The one called Hazel told us this, but we will determine the truth. Come.”

Leo didn’t like the sound of determine the truth. It made him think of torture racks and red-hot pokers.

He followed the fish centaur through a massive forest of kelp. Leo could’ve darted to one side and gotten lost in the plants pretty easily, but he didn’t try. For one thing, he figured Aphros could travel much faster in the water, and the guy might be able to shut off the magic that let Leo move and breathe. Inside or outside the cave, Leo was just as much a captive.

Also, Leo had no clue where he was.

They drifted between rows of kelp as tall as apartment buildings. The green-and-yellow plants swayed weightlessly, like columns of helium balloons. High above, Leo saw a smudge of white that might have been the sun.

He guessed that meant they’d been here overnight. Was the Argo II all right? Had it sailed on without them, or were their friends still searching?

Leo couldn’t even be sure how deep they were. Plants could grow here—so not too deep, right? Still, he knew he couldn’t just swim for the surface. He’d heard about people who ascended too quickly and developed nitrogen bubbles in their blood. Leo wanted to avoid carbonated blood.

They drifted along for maybe half a mile. Leo was tempted to ask where Aphros was taking him, but the big sword strapped to the centaur’s back sort of discouraged conversation.

Finally the kelp forest opened up. Leo gasped. They were standing (swimming, whatever) at the summit of a high underwater hill. Below them stretched an entire town of Greek-style buildings on the seafloor.

The roofs were tiled with mother-of-pearl. The gardens were filled with coral and sea anemones. Hippocampi grazed in a field of seaweed. A team of Cyclopes was placing the domed roof on a new temple, using a blue whale as a crane. And swimming through the streets, hanging out in the courtyards, practicing combat with tridents and swords in the arena were dozens of mermen and mermaids—honest-to-goodness fish-people.

Leo had seen a lot of crazy stuff, but he had always thought merpeople were silly fictional creatures, like Smurfs or Muppets.

There was nothing silly or cute about these merpeople, though. Even from a distance, they looked fierce and not at all human. Their eyes glowed yellow. They had sharklike teeth and leathery skin in colors ranging from coral red to ink black.

“It’s a training camp,” Leo realized. He looked at Aphros in awe. “You train heroes, the same way Chiron does?”

Aphros nodded, a glint of pride in his eyes. “We have trained all the famous mer-heroes! Name a mer-hero, and we have trained him or her!”

“Oh, sure,” Leo said. “Like…um, the Little Mermaid?”

Aphros frowned. “Who? No! Like Triton, Glaucus, Weissmuller, and Bill!”

“Oh.” Leo had no idea who any of those people were. “You trained Bill? Impressive.”

“Indeed!” Aphros pounded his chest. “I trained Bill myself. A great merman.”

“You teach combat, I guess.”

Aphros threw up his hands in exasperation. “Why does everyone assume that?”

Leo glanced at the massive sword on the fish-guy’s back. “Uh, I don’t know.”

“I teach music and poetry!” Aphros said. “Life skills! Homemaking! These are important for heroes.”

“Absolutely.” Leo tried to keep a straight face. “Sewing? Cookie baking?”

“Yes. I’m glad you understand. Perhaps later, if I don’t have to kill you, I will share my brownie recipe.” Aphros gestured behind him contemptuously. “My brother Bythos—he teaches combat.”

Leo wasn’t sure whether he felt relieved or insulted that the combat trainer was interrogating Frank, while Leo got the home economics teacher. “So, great. This is Camp…what do you call it? Camp Fish-Blood?”

Aphros frowned. “I hope that was a joke. This is Camp __________.” He made a sound that was a series of sonar pings and hisses.

“Silly me,” Leo said. “And, you know, I could really go for some of those brownies! So what do we have to do to get to the not killing me stage?”

“Tell me your story,” Aphros said.

Leo hesitated, but not for long. Somehow he sensed that he should tell the truth. He started at the beginning—how Hera had been his babysitter and placed him in the flames; how his mother had died because of Gaea, who had identified Leo as a future enemy. He talked about how he had spent his childhood bouncing around in foster homes, until he and Jason and Piper had been taken to Camp Half-Blood. He explained the Prophecy of Seven, the building of the Argo II, and their quest to reach Greece and defeat the giants before Gaea woke.

As he talked, Aphros drew some wicked-looking metal spikes from his belt. Leo was afraid he had said something wrong, but Aphros pulled some seaweed yarn from his pouch and started knitting. “Go on,” he urged. “Don’t stop.”

By the time Leo had explained the eidolons, the problem with the Romans, and all the troubles the Argo II had encountered crossing the United States and embarking from Charleston, Aphros had knitted a complete baby bonnet.

Leo waited while the fish centaur put away his supplies. Aphros’s lobster-claw horns kept swimming around in his thick hair, and Leo had to resist the urge to try to rescue them.

“Very well,” Aphros said. “I believe you.”

“As simple as that?”

“I am quite good at discerning lies. I hear none from you. Your story also fits with what Hazel Levesque told us.”

“Is she—?”

“Of course,” Aphros said. “She’s fine.” He put his fingers to his mouth and whistled, which sounded strange underwater—like a dolphin screaming. “My people will bring her here shortly. You must understand…our location is a carefully guarded secret. You and your friends showed up in a warship, pursued by one of Keto’s sea monsters. We did not know whose side you were on.”

“Is the ship all right?”

“Damaged,” Aphros said, “but not terribly. The skolopendra withdrew after it got a mouthful of fire. Nice touch.”

“Thank you. Skolopendra? Never heard of it.”

“Consider yourself lucky. They are nasty creatures. Keto must really hate you. At any rate, we rescued you and the other two from the creature’s tentacles as it retreated into the deep. Your friends are still above, searching for you; but we have obscured their vision. We had to be sure you were not a threat. Otherwise, we would have had to…take measures.”

Leo gulped. He was pretty sure taking measures did not mean baking extra brownies. And if these guys were so powerful that they could keep their camp hidden from Percy, who had all those Poseidonish water powers, they were not fish dudes to mess with. “So…we can go?”

“Soon,” Aphros promised. “I must check with Bythos. When he is done talking with your friend Gank—”

“Frank.”

“Frank. When they are done, we will send you back to your ship. And we may have some warnings for you.”

“Warnings?”

“Ah.” Aphros pointed. Hazel emerged from the kelp forest, escorted by two vicious-looking mermaids, who were baring their fangs and hissing. Leo thought Hazel might be in danger. Then he saw she was completely at ease, grinning and talking with her escorts, and Leo realized that the mermaids were laughing.

“Leo!” Hazel paddled toward him. “Isn’t this place amazing?”

They were left alone at the ridge, which must have meant Aphros really did trust them. While the centaur and the mermaids went off to fetch Frank, Leo and Hazel floated above the hill and gazed down at the underwater camp.

Hazel told him how the mermaids had warmed up to her right away. Aphros and Bythos had been fascinated by her story, as they had never met a child of Pluto before. On top of that, they had heard many legends about the horse Arion, and they were amazed that Hazel had befriended him.

Hazel had promised to visit again with Arion. The mermaids had written their phone numbers in waterproof ink on Hazel’s arm so that she could keep in touch. Leo didn’t even want to ask how mermaids got cell-phone coverage in the middle of the Atlantic.

As Hazel talked, her hair floated around her face in a cloud—like brown earth and gold dust in a miner’s pan. She looked very sure of herself and very beautiful—not at all like the shy, nervous girl in that New Orleans schoolyard with her smashed canvas lunch bag at her feet.

“We didn’t get to talk,” Leo said. He was reluctant to bring up the subject, but he knew this might be their only chance to be alone. “I mean about Sammy.”

Her smile faded. “I know…I just need some time to let it sink in. It’s strange to think that you and he…”

She didn’t need to finish the thought. Leo knew exactly how strange it was.

“I’m not sure I can explain this to Frank,” she added. “About you and me holding hands.”

She wouldn’t meet Leo’s eyes. Down in the valley, the Cyclopes work crew cheered as the temple roof was set in place.

“I talked to him,” Leo said. “I told him I wasn’t trying to…you know. Make trouble between you two.”

“Oh. Good.”

Did she sound disappointed? Leo wasn’t sure, and he wasn’t sure he wanted to know.

“Frank, um, seemed pretty freaked out when I summoned fire.” Leo explained what had happened in the cave.

Hazel looked stunned. “Oh, no. That would terrify him.”

Her hand went to her denim jacket, like she was checking for something in the inside pocket. She always wore that jacket, or some sort of overshirt, even when it was hot outside. Leo had assumed that she did it out of modesty, or because it was better for horseback riding, like a motorcycle jacket. Now he began to wonder.

His brain shifted into high gear. He remembered what Frank had said about his weakness…a piece of firewood. He thought about why this kid would have a fear of fire, and why Hazel would be so attuned to those feelings. Leo thought about some of the stories he’d heard at Camp Half-Blood. For obvious reasons, he tended to pay attention to legends about fire. Now he remembered one he hadn’t thought about in months.

“There was an old legend about a hero,” he recalled. “His lifeline was tied to a stick in a fireplace, and when that piece of wood burned up…”

Hazel’s expression turned dark. Leo knew he’d struck on the truth.

“Frank has that problem,” he guessed. “And the piece of firewood…” He pointed at Hazel’s jacket. “He gave it to you for safekeeping?”

“Leo, please don’t…I can’t talk about it.”

Leo’s instincts as a mechanic kicked in. He started thinking about the properties of wood and the corrosiveness of salt water. “Is the firewood okay in the ocean like this? Does the layer of air around you protect it?”

“It’s fine,” Hazel said. “The wood didn’t even get wet. Besides, it’s wrapped up in several layers of cloth and plastic and—” She bit her lip in frustration. “And I’m not supposed to talk about it! Leo, the point is if Frank seems afraid of you, or uneasy, you’ve got to understand…”

Leo was glad he was floating, because he probably would’ve been too dizzy to stand. He imagined being in Frank’s position, his life so fragile, it literally could burn up at any time. He imagined how much trust it would take to give his lifeline—his entire fate—to another person.

Frank had chosen Hazel, obviously. So when he had seen Leo—a guy who could summon fire at will—moving in on his girl…

Leo shuddered. No wonder Frank didn’t like him. And suddenly Frank’s ability to turn into a bunch of different animals didn’t seem so awesome—not if it came with a big catch like that.

Leo thought about his least favorite line in the Prophecy of Seven: To storm or fire the world must fall. For a long time, he’d figured that Jason or Percy stood for storm—maybe both of them together. Leo was the fire guy. Nobody said that, but it was pretty clear. Leo was one of the wild cards. If he did the wrong thing, the world could fall. No…it must fall. Leo wondered if Frank and his firewood had something to do with that line. Leo had already made some epic mistakes. It would be so easy for him to accidentally send Frank Zhang up in flames.

“There you are!” Bythos’s voice made Leo flinch.

Bythos and Aphros floated over with Frank between them, looking pale but okay. Frank studied Hazel and Leo carefully, as if trying to read what they’d been talking about.

“You are free to go,” Bythos said. He opened his saddlebags and returned their confiscated supplies. Leo had never been so glad to fit his tool belt around his waist.

“Tell Percy Jackson not to worry,” Aphros said. “We have understood your story about the imprisoned sea creatures in Atlanta. Keto and Phorcys must be stopped. We will send a quest of mer-heroes to defeat them and free their captives. Perhaps Cyrus?”

“Or Bill,” Bythos offered.

“Yes! Bill would be perfect,” Aphros agreed. “At any rate, we are grateful that Percy brought this to our attention.”

“You should talk to him in person,” Leo suggested. “I mean, son of Poseidon, and all.”

Both fish-centaurs shook their heads solemnly. “Sometimes it is best not to interact with Poseidon’s brood,” Aphros said. “We are friendly with the sea god, of course; but the politics of undersea deities is…complicated. And we value our independence. Nevertheless, tell Percy thank you. We will do what we can to speed you safely across the Atlantic without further interference from Keto’s monsters, but be warned: in the ancient sea, the Mare Nostrum, more dangers await.”

Frank sighed. “Naturally.”

Bythos clapped the big guy on the shoulder. “You will be fine, Frank Zhang. Keep practicing those sea life transformations. The koi fish is good, but try for a Portuguese man-of-war. Remember what I showed you. It’s all in the breathing.”

Frank looked mortally embarrassed. Leo bit his lip, determined not to smile.

“And you, Hazel,” Aphros said, “come visit again, and bring that horse of yours! I know you are concerned about the time you lost, spending the night in our realm. You are worried about your brother, Nico.…”

Hazel gripped her cavalry sword. “Is he—do you know where he is?”

Aphros shook his head. “Not exactly. But when you get closer, you should be able to sense his presence. Never fear! You must reach Rome the day after tomorrow if you are to save him, but there is still time. And you must save him.”

“Yes,” Bythos agreed. “He will be essential for your journey. I am not sure how, but I sense it is true.”

Aphros planted his hand on Leo’s shoulder. “As for you, Leo Valdez, stay close to Hazel and Frank when you reach Rome. I sense they will face…ah, mechanical difficulties that only you can overcome.”

“Mechanical difficulties?” Leo asked.

Aphros smiled as if that was great news. “And I have gifts for you, the brave navigator of the Argo II!”

“I like to think of myself as captain,” Leo said. “Or supreme commander.”

“Brownies!” Aphros said proudly, shoving an old-fashioned picnic basket into Leo’s arms. It was surrounded by a bubble of air, which Leo hoped would keep the brownies from turning into saltwater fudge sludge. “In this basket you will also find the recipe. Not too much butter! That’s the trick. And I’ve given you a letter of introduction to Tiberinus, the god of the Tiber River. Once you reach Rome, your friend the daughter of Athena will need this.”

“Annabeth…” Leo said. “Okay, but why?”

Bythos laughed. “She follows the Mark of Athena, doesn’t she? Tiberinus can guide her in this quest. He’s an ancient, proud god who can be…difficult; but letters of introduction are everything to Roman spirits. This will convince Tiberinus to help her. Hopefully.”

“Hopefully,” Leo repeated.

Bythos produced three small pink pearls from his saddlebags. “And now, off with you, demigods! Good sailing!”

He threw a pearl at each of them in turn, and three shimmering pink bubbles of energy formed around them.

They began to rise through the water. Leo just had time to think: A hamster ball elevator? Then he gained speed and rocketed toward the distant glow of the sun above.

PIPER HAD A NEW ENTRY in her top-ten list of Times Piper Felt Useless.

Fighting Shrimpzilla with a dagger and a pretty voice? Not so effective. Then the monster had sunk into the deep and disappeared along with three of her friends, and she’d been powerless to help them.

Afterward, Annabeth, Coach Hedge, and Buford the table rushed around repairing things so that the ship wouldn’t sink. Percy, despite being exhausted, searched the ocean for their missing friends. Jason, also exhausted, flew around the rigging like a blond Peter Pan, putting out fires from the second green explosion that had lit up the sky just above the mainmast.

As for Piper, all she could do was stare at her knife Katoptris, trying to locate Leo, Hazel, and Frank. The only images that came to her were ones she didn’t want to see: three black SUVs driving north from Charleston, packed with Roman demigods, Reyna sitting at the wheel of the lead car. Giant eagles escorted them from above. Every so often, glowing purple spirits in ghostly chariots appeared out of the countryside and fell in behind them, thundering up I-95 toward New York and Camp Half-Blood.

Piper concentrated harder. She saw the nightmarish images she had seen before: the human-headed bull rising from the water, then the dark well-shaped room filling with black water as Jason, Percy, and she struggled to stay afloat.

She sheathed Katoptris, wondering how Helen of Troy had stayed sane during the Trojan War, if this blade had been her only source of news. Then she remembered that everyone around Helen had been slaughtered by the invading Greek army. Maybe she hadn’t stayed sane.

By the time the sun rose, none of them had slept. Percy had scoured the seafloor and found nothing. The Argo II was no longer in danger of sinking, though without Leo, they couldn’t do full repairs. The ship was capable of sailing, but no one suggested leaving the area—not without their missing friends.

Piper and Annabeth sent a dream vision to Camp Half-Blood, warning Chiron of what had happened with the Romans at Fort Sumter. Annabeth explained her exchange of words with Reyna. Piper relayed the vision from her knife about the SUVs racing north. The kindly centaur’s face seemed to age thirty years during the course of their conversation, but he assured them he would see to the defenses of the camp. Tyson, Mrs. O’Leary, and Ella had arrived safely. If necessary, Tyson could summon an army of Cyclopes to the camp’s defense, and Ella and Rachel Dare were already comparing prophecies, trying to learn more about what the future held. The job of the seven demigods aboard the Argo II, Chiron reminded them, was to finish the quest and come back safely.

After the Iris-message, the demigods paced the deck in silence, staring at the water and hoping for a miracle.

When it finally came—three giant pink bubbles bursting at the surface off the starboard bow and ejecting Frank, Hazel, and Leo—Piper went a little crazy. She cried out with relief and dove straight into the water.

What was she thinking? She didn’t take a rope or a life vest or anything. But at the moment, she was just so happy that she paddled over to Leo and kissed him on the cheek, which kind of surprised him.

“Miss me?” Leo laughed.

Piper was suddenly furious. “Where were you? How are you guys alive?”

“Long story,” he said. A picnic basket bobbed to the surface next to him. “Want a brownie?”

Once they got on board and changed into dry clothes (poor Frank had to borrow a pair of too-small pants from Jason) the crew all gathered on the quarterdeck for a celebratory breakfast—except for Coach Hedge, who grumbled that the atmosphere was getting too cuddly for his tastes and went below to hammer out some dents in the hull. While Leo fussed over his helm controls, Hazel and Frank related the story of the fish-centaurs and their training camp.

“Incredible,” Jason said. “These are really good brownies.”

“That’s your only comment?” Piper demanded.

He looked surprised. “What? I heard the story. Fish-centaurs. Merpeople. Letter of intro to the Tiber River god. Got it. But these brownies—”

“I know,” Frank said, his mouth full. “Try them with Esther’s peach preserves.”

“That,” Hazel said, “is incredibly disgusting.”

“Pass me the jar, man,” Jason said.

Hazel and Piper exchanged a look of total exasperation. Boys.

Percy, for his part, wanted to hear every detail about the aquatic camp. He kept coming back to one point: “They didn’t want to meet me?”

“It wasn’t that,” Hazel said. “Just…undersea politics, I guess. The merpeople are territorial. The good news is they’re taking care of that aquarium in Atlanta. And they’ll help protect the Argo II as we cross the Atlantic.”

Percy nodded absently. “But they didn’t want to meet me?”

Annabeth swatted his arm. “Come on, Seaweed Brain! We’ve got other things to worry about.”

“She’s right,” Hazel said. “After today, Nico has less than two days. The fish-centaurs said we have to rescue him. He’s essential to the quest somehow.”

She looked around defensively, as if waiting for someone to argue. No one did. Piper tried to imagine what Nico di Angelo was feeling, stuck in a jar with only two pomegranate seeds left to sustain him, and no idea whether he would be rescued. It made Piper anxious to reach Rome, even though she had a horrible feeling she was sailing toward her own sort of prison—a dark room filled with water.

“Nico must have information about the Doors of Death,” Piper said. “We’ll save him, Hazel. We can make it in time. Right, Leo?”

“What?” Leo tore his eyes away from the controls. “Oh, yeah. We should reach the Mediterranean tomorrow morning. Then spend the rest of that day sailing to Rome, or flying, if I can get the stabilizer fixed by then.…”

Jason suddenly looked as though his brownie with peach preserves didn’t taste so good. “Which will put us in Rome on the last possible day for Nico. Twenty-four hours to find him—at most.”

Percy crossed his legs. “And that’s only part of the problem. There’s the Mark of Athena, too.”

Annabeth didn’t seem happy with the change of topic. She rested her hand on her backpack, which, since they’d left Charleston, she always seemed to have with her.

She opened the bag and brought out a thin bronze disk the diameter of a donut. “This is the map that I found at Fort Sumter. It’s…”

She stopped abruptly, staring at the smooth bronze surface. “It’s blank!”

Percy took it and examined both sides. “It wasn’t like this earlier?”

“No! I was looking at it in my cabin and…” Annabeth muttered under her breath. “It must be like the Mark of Athena. I can only see it when I’m alone. It won’t show itself to other demigods.”

Frank scooted back like the disk might explode. He had an orange-juice mustache and a brownie-crumb beard that made Piper want to hand him a napkin.

“What did it have on it?” Frank asked nervously. “And what is the Mark of Athena? I still don’t get it.”

Annabeth took the disk from Percy. She turned it in the sunlight, but it remained blank. “The map was hard to read, but it showed a spot on the Tiber River in Rome. I think that’s where my quest starts…the path I’ve got to take to follow the Mark.”

“Maybe that’s where you meet the river god Tiberinus,” Piper said. “But what is the Mark?”

“The coin,” Annabeth murmured.

Percy frowned. “What coin?”

Annabeth dug into her pocket and brought out a silver drachma. “I’ve been carrying this ever since I saw my mom at Grand Central. It’s an Athenian coin.”

She passed it around. While each demigod looked at it, Piper had a ridiculous memory of show-and-tell in elementary school.

“An owl,” Leo noted. “Well, that makes sense. I guess the branch is an olive branch? But what’s this inscription, ΑΘΕ—Area Of Effect?”

“It’s alpha, theta, epsilon,” Annabeth said. “In Greek it stands for Of The Athenians…or you could read it as the children of Athena. It’s sort of the Athenian motto.”

“Like SPQR for the Romans,” Piper guessed.

Annabeth nodded. “Anyway, the Mark of Athena is an owl, just like that one. It appears in fiery red. I’ve seen it in my dreams. Then twice at Fort Sumter.”

She described what had happened at the fort—the voice of Gaea, the spiders in the garrison, the Mark burning them away. Piper could tell it wasn’t easy for her to talk about.

Percy took Annabeth’s hand. “I should have been there for you.”

“But that’s the point,” Annabeth said. “No one can be there for me. When I get to Rome, I’ll have to strike out on my own. Otherwise, the Mark won’t appear. I’ll have to follow it to…to the source.”

Frank took the coin from Leo. He stared at the owl. “The giants’ bane stands gold and pale, Won with pain from a woven jail.” He looked up at Annabeth. “What is it…this thing at the source?”

Before Annabeth could answer, Jason spoke up.

“A statue,” he said. “A statue of Athena. At least…that’s my guess.”

Piper frowned. “You said you didn’t know.”

“I don’t. But the more I think about it…there’s only one artifact that could fit the legend.” He turned to Annabeth. “I’m sorry. I should have told you everything I’ve heard, much earlier. But honestly, I was scared. If this legend is true—”

“I know,” Annabeth said. “I figured it out, Jason. I don’t blame you. But if we manage to save the statue, Greek and Romans together…Don’t you see? It could heal the rift.”

“Hold on.” Percy made a time-out gesture. “What statue?”

Annabeth took back the silver coin and slipped it into her pocket. “The Athena Parthenos,” she said. “The most famous Greek statue of all time. It was forty feet tall, covered in ivory and gold. It stood in the middle of the Parthenon in Athens.”

The ship went silent, except for the waves lapping against the hull.

“Okay, I’ll bite,” Leo said at last. “What happened to it?”

“It disappeared,” Annabeth said.

Leo frowned. “How does a forty-foot-tall statue in the middle of the Parthenon just disappear?”

“That’s a good question,” Annabeth said. “It’s one of the biggest mysteries in history. Some people thought the statue was melted down for its gold, or destroyed by invaders. Athens was sacked a number of times. Some thought the statue was carried off—”

“By Romans,” Jason finished. “At least, that’s one theory, and it fits the legend I heard at Camp Jupiter. To break the Greeks’ spirit, the Romans carted off the Athena Parthenos when they took over the city of Athens. They hid it in an underground shrine in Rome. The Roman demigods swore it would never see the light of day. They literally stole Athena, so she could no longer be the symbol of Greek military power. She became Minerva, a much tamer goddess.”

“And the children of Athena have been searching for the statue ever since,” Annabeth said. “Most don’t know about the legend, but in each generation, a few are chosen by the goddess. They’re given a coin like mine. They follow the Mark of Athena…a kind of magical trail that links them to the statue…hoping to find the resting place of the Athena Parthenos and get the statue back.”

Piper watched the two of them—Annabeth and Jason—with quiet amazement. They spoke like a team, without any hostility or blame. The two of them had never really trusted each other. Piper was close enough to both of them to know that. But now…if they could discuss such a huge problem so calmly—the ultimate source of Greek/Roman hatred—maybe there was hope for the two camps, after all.

Percy seemed be having similar thoughts, judging from his surprised expression. “So if we—I mean you—find the statue…what would we do with it? Could we even move it?”

“I’m not sure,” Annabeth admitted. “But if we could save it somehow, it could unite the two camps. It could heal my mother of this hatred she’s got, tearing her two aspects apart. And maybe…maybe the statue has some sort of power that could help us against the giants.”

Piper stared at Annabeth with awe, just starting to appreciate the huge responsibility her friend had taken on. And Annabeth meant to do it alone.

“This could change everything,” Piper said. “It could end thousands of years of hostility. It might be the key to defeating Gaea. But if we can’t help you…”

She didn’t finish, but the question seemed to hang in the air: Was saving the statue even possible?

Annabeth squared her shoulders. Piper knew she must be terrified inside, but she did a good job hiding it.

“I have to succeed,” Annabeth said simply. “The risk is worth it.”

Hazel twirled her hair pensively. “I don’t like the idea of you risking your life alone, but you’re right. We saw what recovering the golden eagle standard did for the Roman legion. If this statue is the most powerful symbol of Athena ever created—”

“It could kick some serious booty,” Leo offered.

Hazel frowned. “That wasn’t the way I’d put it, but yes.”

“Except…” Percy took Annabeth’s hand again. “No child of Athena has ever found it. Annabeth, what’s down there? What’s guarding it? If it’s got to do with spiders—?”

“Won through pain from a woven jail,” Frank recalled. “Woven, like webs?”

Annabeth’s face turned as white as printer paper. Piper suspected that Annabeth knew what awaited her…or at least that she had a very good idea. She was trying to hold down a wave of panic and terror.

“We’ll deal with that when we get to Rome,” Piper suggested, putting a little charmspeak in her voice to soothe her friend’s nerves. “It’s going to work out. Annabeth is going to kick some serious booty, too. You’ll see.”

“Yeah,” Percy said. “I learned a long time ago: Never bet against Annabeth.”

Annabeth looked at them both gratefully.

Judging from their half-eaten breakfasts, the others still felt uneasy; but Leo managed to shake them out of it. He pushed a button, and a loud blast of steam exploded from Festus’s mouth, making everyone jump.

“Well!” he said. “Good pep rally, but there’s still a ton of things to fix on this ship before we get to the Mediterranean. Please report to Supreme Commander Leo for your superfun list of chores!”

Piper and Jason took charge of cleaning the lower deck, which had been thrown into chaos during the monster attack. Reorganizing sickbay and battening down the storage area took them most of the day, but Piper didn’t mind. For one thing, she got to spend time with Jason. For another, last night’s explosions had given Piper a healthy respect for Greek fire. She didn’t want any loose vials of that stuff rolling through the corridors in the middle of the night.

As they were fixing up the stables, Piper thought about the night Annabeth and Percy had spent down here accidentally. Piper wished that she could talk with Jason all night—just curl up on the stable floor and enjoy being with him. Why didn’t they get to break the rules?

But Jason wasn’t like that. He was hardwired to be a leader and set a good example. Breaking the rules didn’t come naturally to him.

No doubt Reyna admired that about him. Piper did too…mostly.

The one time she’d convinced him to be a rebel was back at the Wilderness School, when they had sneaked onto the roof at night to watch a meteor shower. That’s where they’d had their first kiss.

Unfortunately, that memory was a trick of the Mist, a magical lie implanted in her head by Hera. Piper and Jason were together now, in real life, but their relationship had been founded on an illusion. If Piper tried to get the real Jason to sneak out at night, would he do it?

She swept the hay into piles. Jason fixed a broken door on one of the stables. The glass floor hatch glowed from the ocean below—a green expanse of light and shadow that seemed to go down forever. Piper kept glancing over, afraid she’d see a monster’s face peeping in, or the water cannibals from her grandfather’s old stories; but all she saw was an occasional school of herring.

As she watched Jason work, she admired how easily he did each task, whether it was fixing a door or oiling saddles. It wasn’t just his strong arms and his skillful hands, though Piper liked those just fine, but the way he acted so upbeat and confident. He did what needed to be done without complaint. He kept his sense of humor, despite the fact that the guy had to be dead on his feet after not having slept the night before. Piper couldn’t blame Reyna for having a crush on him. When it came to work and duty, Jason was Roman to the core.

Piper thought about her mother’s tea party in Charleston. She wondered what the goddess had told Reyna a year ago, and why it had changed the way Reyna treated Jason. Had Aphrodite encouraged or discouraged her to like Jason?

Piper wasn’t sure, but she wished her mom hadn’t appeared in Charleston. Regular mothers were embarrassing enough. Godly glamour moms who invited your friends over for tea and guy talk—that was just mortifying.

Aphrodite had paid so much attention to Annabeth and Hazel, it had made Piper uneasy. When her mom got interested in somebody’s love life, usually that was a bad sign. It meant trouble was coming. Or as Aphrodite would say, twists and turns.

But also, Piper was secretly hurt not to have her mother to herself. Aphrodite had barely looked at her. She hadn’t said a word about Jason. She hadn’t bothered explaining her conversation with Reyna at all.

It was almost as if Aphrodite no longer found Piper interesting. Piper had gotten her guy. Now it was up to her to make things work, and Aphrodite had moved on to newer gossip as easily as she might toss out an old copy of a tabloid magazine.

All of you are such excellent stories, Aphrodite had said. I mean, girls.

Piper hadn’t appreciated that, but part of her had thought: Fine. I don’t want to be a story. I want a nice steady life with a nice steady boyfriend.

If only she knew more about making relationships work. She was supposed to be an expert, being the head counselor for Aphrodite cabin. Other campers at Camp Half-Blood came to her for advice all the time. Piper had tried to do her best, but with her own boyfriend, she was clueless. She was constantly second-guessing herself, reading too much into Jason’s expressions, his moods, his offhand comments. Why did it have to be so hard? Why couldn’t there be a happily-ever-after ride-into-the-sunset feeling all the time?

“What are you thinking?” Jason asked.

Piper realized she’d been making a sour face. In the reflection of the glass bay doors, she looked like she’d swallowed a teaspoon of salt.

“Nothing,” she said. “I mean…a lot of things. Kind of all at once.”

Jason laughed. The scar on his lip almost disappeared when he smiled. Considering all the stuff he’d been through, it was amazing that he could be in such a good mood.

“It’s going to work out,” he promised. “You said so yourself.”

“Yeah,” Piper agreed. “Except I was just saying that to make Annabeth feel better.”

Jason shrugged. “Still, it’s true. We’re almost to the ancient lands. We’ve left the Romans behind.”

“And now they’re on their way to Camp Half-Blood to attack our friends.”

Jason hesitated, as if it was hard for him to put a positive spin on that. “Chiron will find a way to stall them. The Romans might take weeks to actually find the camp and plan their attack. Besides, Reyna will do what she can to slow things down. She’s still on our side. I know she is.”

“You trust her.” Piper’s voice sounded hollow, even to herself.

“Look, Pipes. I told you, you’ve got nothing to be jealous about.”

“She’s beautiful. She’s powerful. She’s so…Roman.”

Jason put down his hammer. He took her hand, which sent a tingle up her arm. Piper’s dad had once taken her to the Aquarium of the Pacific and shown her an electric eel. He told her that the eel sent out pulses that shocked and paralyzed its prey. Every time Jason looked at her or touched her hand, Piper felt like that.

“You’re beautiful and powerful,” he said. “And I don’t want you to be Roman. I want you to be Piper. Besides, we’re a team, you and me.”

She wanted to believe him. They’d been together, really, for months now. Still, she couldn’t get rid of her doubts, any more than Jason could get rid of the SPQR tattoo burned on his forearm.

Above them, the ship’s bell rang for dinner.

Jason smirked. “We’d better get up there. We don’t want Coach Hedge tying bells around our necks.”

Piper shuddered. Coach Hedge had threatened to do that after the Percy/Annabeth scandal, so he’d know if anyone sneaked out at night.

“Yeah,” she said regretfully, looking at the glass doors below their feet. “I guess we need dinner…and a good night’s sleep.”

THE NEXT MORNING PIPER WOKE to a different ship’s horn—a blast so loud it literally shook her out of bed.

She wondered if Leo was pulling another joke. Then the horn boomed again. It sounded like it was coming from several hundred yards away—from another vessel.

She rushed to get dressed. By the time she got up on deck, the others had already gathered—all hastily dressed except for Coach Hedge, who had pulled the night watch.

Frank’s Vancouver Winter Olympics shirt was inside out. Percy wore pajama pants and a bronze breastplate, which was an interesting fashion statement. Hazel’s hair was all blown to one side, as though she’d walked through a cyclone; and Leo had accidentally set himself on fire. His T-shirt was in charred tatters. His arms were smoking.

About a hundred yards to port, a massive cruise ship glided past. Tourists waved at them from fifteen or sixteen rows of balconies. Some smiled and took pictures. None of them looked surprised to see an Ancient Greek trireme. Maybe the Mist made it look like a fishing boat, or perhaps the cruisers thought the Argo II was a tourist attraction.

The cruise ship blew its horn again, and the Argo II had a shaking fit.

Coach Hedge plugged his ears. “Do they have to be so loud?”

“They’re just saying hi,” Frank speculated.

“WHAT?” Hedge yelled back.

The ship edged past them, heading out to sea. The tourists kept waving. If they found it strange that the Argo II was populated by half-asleep kids in armor and pajamas and a man with goat legs, they didn’t let on.

“Bye!” Leo called, raising his smoking hand.

“Can I man the ballistae?” Hedge asked.

“No,” Leo said through a forced smile.

Hazel rubbed her eyes and looked across the glittering green water. “Where are—oh…Wow.”

Piper followed her gaze and gasped. Without the cruise ship blocking their view, she saw a mountain jutting from the sea less than half a mile to the north. Piper had seen impressive cliffs before. She’d driven Highway 1 along the California coast. She’d even fallen down the Grand Canyon with Jason and flown back up. But neither was as amazing as this massive fist of blinding white rock thrust into the sky. On one side, the limestone cliffs were almost completely sheer, dropping into the sea over a thousand feet below, as near as Piper could figure. On the other side, the mountain sloped in tiers, covered in green forest, so that the whole thing reminded Piper of a colossal sphinx, worn down over the millennia, with a massive white head and chest, and a green cloak over its back.

“The Rock of Gibraltar,” Annabeth said in awe. “At the tip of Spain. And over there—” She pointed south, to a more distant stretch of red and ochre hills. “That must be Africa. We’re at the mouth of the Mediterranean.”

The morning was warm, but Piper shivered. Despite the wide stretch of sea in front of them, she felt like she was standing at an impassable barrier. Once in the Mediterranean—the Mare Nostrum—they would be in the ancient lands. If the legends were true, their quest would become ten times more dangerous.

“What now?” she asked. “Do we just sail in?”

“Why not?” Leo said. “It’s a big shipping channel. Boats go in and out all the time.”

Not triremes full of demigods, Piper thought.

Annabeth gazed at the Rock of Gibraltar. Piper recognized that brooding expression on her friend’s face. It almost always meant that she anticipated trouble.

“In the old days,” Annabeth said, “they called this area the pillars of Hercules. The Rock was supposed to be one pillar. The other was one of the African mountains. Nobody is sure which one.”

“Hercules, huh?” Percy frowned. “That guy was like the Starbucks of Ancient Greece. Everywhere you turn—there he is.”

A thunderous boom shook the Argo II, though Piper wasn’t sure where it came from this time. She didn’t see any other ships, and the skies were clear.

Her mouth suddenly felt dry. “So…these Pillars of Hercules. Are they dangerous?”

Annabeth stayed focused on the white cliffs, as if waiting for the Mark of Athena to blaze to life. “For Greeks, the pillars marked the end of the known world. The Romans said the pillars were inscribed with a Latin warning—”

“Non plus ultra,” Percy said.

Annabeth looked stunned. “Yeah. Nothing Further Beyond. How did you know?”

Percy pointed. “Because I’m looking at it.”

Directly ahead of them, in the middle of the straits, an island had shimmered into existence. Piper was positive no island had been there before. It was a small hilly mass of land, covered in forests and ringed with white beaches. Not very impressive compared to Gibraltar, but in front of the island, jutting from waves about a hundred yards offshore, were two white Grecian columns as tall as the Argo’s masts. Between the columns, huge silver words glittered underwater—maybe an illusion, or maybe inlaid in the sand: NON PLUS ULTRA.

“Guys, do I turn around?” Leo asked nervously. “Or…”

No one answered—maybe because, like Piper, they had noticed the figure standing on the beach. As the ship approached the columns, she saw a dark-haired man in purple robes, his arms crossed, staring intently at their ship as if he were expecting them. Piper couldn’t tell much else about him from this distance, but judging from his posture, he wasn’t happy.

Frank inhaled sharply. “Could that be—?”

“Hercules,” Jason said. “The most powerful demigod of all time.”

The Argo II was only a few hundred yards from the columns now.

“Need an answer,” Leo said urgently. “I can turn, or we can take off. The stabilizers are working again. But I need to know quick—”

“We have to keep going,” Annabeth said. “I think he’s guarding these straits. If that’s really Hercules, sailing or flying away wouldn’t do any good. He’ll want to talk to us.”

Piper resisted the urge to use charmspeak. She wanted to yell at Leo: Fly! Get us out of here! Unfortunately, she had a feeling that Annabeth was right. If they wanted to pass into the Mediterranean, they couldn’t avoid this meeting.

“Won’t Hercules be on our side?” she asked hopefully. “I mean…he’s one of us, right?”

Jason grunted. “He was a son of Zeus, but when he died, he became a god. You can never be sure with gods.”

Piper remembered their meeting with Bacchus in Kansas—another god who used to be a demigod. He hadn’t been exactly helpful.

“Great,” Percy said. “Seven of us against Hercules.”

“And a satyr!” Hedge added. “We can take him.”

“I’ve got a better idea,” Annabeth said. “We send ambassadors ashore. A small group—one or two at most. Try to talk with him.”

“I’ll go,” Jason said. “He’s a son of Zeus. I’m the son of Jupiter. Maybe he’ll be friendly to me.”

“Or maybe he’ll hate you,” Percy suggested. “Half brothers don’t always get along.”

Jason scowled. “Thank you, Mr. Optimism.”

“It’s worth a shot,” Annabeth said. “At least Jason and Hercules have something in common. And we need our best diplomat. Somebody who’s good with words.”

All eyes turned to Piper.

She tried to avoid screaming and jumping over the side. A bad premonition gnawed at her gut. But if Jason was going ashore, she wanted to be with him. Maybe this hugely powerful god would turn out to be helpful. They had to have good luck once in a while, didn’t they?

“Fine,” she said. “Just let me change my clothes.”

Once Leo had anchored the Argo II between the pillars, Jason summoned the wind to carry him and Piper ashore.

The man in purple was waiting for them.

Piper had heard tons of stories about Hercules. She’d seen several cheesy movies and cartoons. Before today, if she had thought about him at all, she’d just roll her eyes and imagine some stupid hairy dude in his thirties with a barrel chest and a gross hippie beard, with a lion skin over his head and a big club, like a caveman. She imagined he would smell bad, belch, and scratch himself a lot, and speak mostly in grunts.

She was not expecting this.

His feet were bare, covered in white sand. His robes made him look like a priest, though Piper couldn’t remember which rank of priest wore purple. Was that cardinals? Bishops? And did the purple color mean he was the Roman version of Hercules rather than the Greek? His beard was fashionably scruffy, like Piper’s dad and his actor friends wore theirs—the sort of I just happened not to shave for two days and I still look awesome look.

He was well built, but not too stocky. His ebony hair was close-cropped, Roman style. He had startling blue eyes like Jason’s, but his skin was coppery, as if he’d spent his entire life on a tanning bed. The most surprising thing: he looked about twenty. Definitely no older. He was handsome in a rugged but not-at-all-caveman way.

He did in fact have a club, which lay in the sand next to him, but it was more like an oversized baseball bat—a five-foot-long polished cylinder of mahogany with a leather handgrip studded in bronze. Coach Hedge would have been jealous.

Jason and Piper landed at the edge of the surf. They approached slowly, careful not to make any threatening moves. Hercules watched them with no particular emotion, as if they were some form of seabird he had never noticed before.

“Hello,” Piper said. Always a good start.

“What’s up?” Hercules said. His voice was deep but casual, very modern. He could’ve been greeting them in the high school locker room.

“Uh, not much.” Piper winced. “Well, actually, a lot. I’m Piper. This is Jason. We—”

“Where’s your lion skin?” Jason interrupted.

Piper wanted to elbow him, but Hercules looked more amused than annoyed.

“It’s ninety degrees out here,” he said. “Why would I wear my lion skin? Do you wear a fur coat to the beach?”

“I guess that makes sense.” Jason sounded disappointed. “It’s just that the pictures always show you with a lion skin.”

Hercules glared at the sky accusingly, like he wanted to have words with his father, Zeus. “Don’t believe everything you hear about me. Being famous isn’t as fun as you might think.”

“Tell me about it,” Piper sighed.

Hercules fixed those brilliant blue eyes on her. “Are you famous?”

“My dad…he’s in the movies.”

Hercules snarled. “Don’t get me started with the movies. Gods of Olympus, they never get anything right. Have you seen one movie about me where I look like me?”

Piper had to admit he had a point. “I’m surprised you’re so young.”

“Ha! Being immortal helps. But, yes, I wasn’t so old when I died. Not by modern standards. I did a lot during my years as a hero…too much, really.” His eyes drifted to Jason. “Son of Zeus, eh?”

“Jupiter,” Jason said.

“Not much difference,” Hercules grumbled. “Dad’s annoying in either form. Me? I was called Heracles. Then the Romans came along and named me Hercules. I didn’t really change that much, though lately just thinking about it gives me splitting headaches…”

The left side of his face twitched. His robes shimmered, momentarily turning white, then back to purple.

“At any rate,” Hercules said, “if you’re Jupiter’s son, you might understand. It’s a lot of pressure. Enough is never enough. Eventually it can make a guy snap.”

He turned to Piper. She felt like a thousand ants were crawling up her back. There was a mixture of sadness and darkness in his eyes that seemed not quite sane, and definitely not safe.

“As for you, my dear,” Hercules said, “be careful. Sons of Zeus can be…well, never mind.”

Piper wasn’t sure what that meant. Suddenly she wanted to get as far from this god as possible, but she tried to maintain a calm, polite expression.

“So, Lord Hercules,” she said, “we’re on a quest. We’d like permission to pass into the Mediterranean.”

Hercules shrugged. “That’s why I’m here. After I died, Dad made me the doorkeeper of Olympus. I said, Great! Palace duty! Party all the time! What he didn’t mention is that I’d be guarding the doors to the ancient lands, stuck on this island for the rest of eternity. Lots of fun.”

He pointed at the pillars rising from the surf. “Stupid columns. Some people claim I created the whole Strait of Gibraltar by shoving mountains apart. Some people say the mountains are the pillars. What a bunch of Augean manure. The pillars are pillars.”

“Right,” Piper said. “Naturally. So…can we pass?”

The god scratched his fashionable beard. “Well, I have to give you the standard warning about how dangerous the ancient lands are. Not just any demigod can survive the Mare Nostrum. Because of that, I have to give you a quest to complete. Prove your worth, blah, blah, blah. Honestly, I don’t make a big deal of it. Usually I give demigods something simple like a shopping trip, singing a funny song, that sort of thing. After all those labors I had to complete for my evil cousin Eurystheus, well…I don’t want to be that guy, you know?”

“Appreciate it,” Jason said.

“Hey, no problem.” Hercules sounded relaxed and easygoing, but he still made Piper nervous. That dark glint in his eyes reminded her of charcoal soaked in kerosene, ready to go up at a moment’s notice.

“So anyway,” Hercules said, “what’s your quest?”

“Giants,” Jason said. “We’re off to Greece to stop them from awakening Gaea.”

“Giants,” Hercules muttered. “I hate those guys. Back when I was a demigod hero…ah, but never mind. So which god put you up to this—Dad? Athena? Maybe Aphrodite?” He raised an eyebrow at Piper. “As pretty as you are, I’m guessing that’s your mom.”

Piper should’ve been thinking faster, but Hercules had unsettled her. Too late, she realized the conversation had become a minefield.

“Hera sent us,” Jason said. “She brought us together to—”

“Hera.” Suddenly Hercules’s expression was like the cliffs of Gibraltar—a solid, unforgiving sheet of stone.

“We hate her too,” Piper said quickly. Gods, why hadn’t it occurred to her? Hera had been Hercules’s mortal enemy. “We didn’t want to help her. She didn’t give us much choice, but—”

“But here you are,” Hercules said, all friendliness gone. “Sorry, you two. I don’t care how worthy your quest is. I don’t do anything that Hera wants. Ever.”

Jason looked mystified. “But I thought you made up with her when you became a god.”

“Like I said,” Hercules grumbled, “don’t believe everything you hear. If you want to pass into the Mediterranean, I’m afraid I’ve got to give you an extra-hard quest.”

“But we’re like brothers,” Jason protested. “Hera’s messed with my life, too. I understand—”

“You understand nothing,” Hercules said coldly. “My first family: dead. My life wasted on ridiculous quests. My second wife dead, after being tricked into poisoning me and leaving me to a painful demise. And my compensation? I got to become a minor god. Immortal, so I can never forget my pain. Stuck here as a gatekeeper, a doorman, a…a butler for the Olympians. No, you don’t understand. The only god who understands me even a little bit is Dionysus. And at least he invented something useful. I have nothing to show except bad film adaptations of my life.”

Piper turned on the charmspeak. “That’s horribly sad, Lord Hercules. But please go easy on us. We’re not bad people.”

She thought she’d succeeded. Hercules hesitated. Then his jaw tightened, and he shook his head. “On the opposite side of this island, over those hills, you’ll find a river. In the middle of that river lives the old god Achelous.”

Hercules waited, as if this information should send them running in terror.

“And… ?” Jason asked.

“And,” Hercules said, “I want you to break off his other horn and bring it to me.”

“He has horns,” Jason said. “Wait…his other horn? What—?”

“Figure it out,” the god snapped. “Here, this should help.”

He said the word help like it meant hurt. From under his robes, Hercules took a small book and tossed it to Piper. She barely caught it.

The book’s glossy cover showed a photographic montage of Greek temples and smiling monsters. The Minotaur was giving the thumbs-up. The title read: The Hercules Guide to the Mare Nostrum.

“Bring me that horn by sundown,” Hercules said. “Just the two of you. No contacting your friends. Your ship will remain where it is. If you succeed, you may pass into the Mediterranean.”

“And if we don’t?” Piper asked, pretty sure she didn’t want the answer.

“Well, Achelous will kill you, obviously,” Hercules said. “And I will break your ship in half with my bare hands and send your friends to an early grave.”

Jason shifted his feet. “Couldn’t we just sing a funny song?”

“I’d get going,” Hercules said coldly. “Sundown. Or your friends are dead.”

THE HERCULES GUIDE TO THE MARE NOSTRUM didn’t help much with snakes and mosquitoes.

“If this is a magic island,” Piper grumbled, “why couldn’t it be a nice magic island?”

They tromped up a hill and down into a heavily wooded valley, careful to avoid the black-and-red-striped snakes sunning themselves on the rocks. Mosquitoes swarmed over stagnant ponds in the lowest areas. The trees were mostly stunted olives, cypress, and pines. The chirring of the cicadas and the oppressive heat reminded Piper of the rez in Oklahoma during the summer.

So far they hadn’t found any river.

“We could fly,” Jason suggested again.

“We might miss something,” Piper said. “Besides, I’m not sure I want to drop in on an unfriendly god. What was his name? Etch-a-Sketch?”

“Achelous.” Jason was trying to read the guidebook while they walked, so he kept running into trees and stumbling over rocks. “Says here he’s a potamus.”

“He’s a hippopotamus?”

“No. Potamus. A river god. According to this, he’s the spirit of some river in Greece.”

“Since we’re not in Greece, let’s assume he’s moved,” Piper said. “Doesn’t bode well for how useful that book is going to be. Anything else?”

“Says Hercules fought him one time,” Jason offered.

“Hercules fought ninety-nine percent of everything in Ancient Greece.”

“Yeah. Let’s see. Pillars of Hercules…” Jason flipped a page. “Says here this island has no hotels, no restaurants, no transportation. Attractions: Hercules and two pillars. Huh, this is interesting. Supposedly the dollar sign—you know, the S with the two lines through it?—that came from the Spanish coat of arms, which showed the Pillars of Hercules with a banner curling between them.”

Great, Piper thought. Jason finally gets along with Annabeth, and her brainiac tendencies start rubbing off on him.

“Anything helpful?” she asked.

“Wait. Here’s a tiny reference to Achelous: This river god fought Hercules for the hand of the beautiful Deianira. During the struggle, Hercules broke off one of the river god’s horns, which became the first cornucopia.”

“Corn of what?”

“It’s that Thanksgiving decoration,” Jason said. “The horn with all the goodies spilling out? We have some in the mess hall at Camp Jupiter. I didn’t know the original one was actually some guy’s horn.”

“And we’re supposed to take his other one,” Piper said. “I’m guessing that won’t be so easy. Who was Deianira?”

“Hercules married her,” Jason said. “I think…doesn’t say here. But I think something bad happened to her.”

Piper remembered what Hercules had told them: his first family dead, his second wife dead after being tricked into poisoning him. She was liking this challenge less and less.

They trudged across a ridge between two hills, trying to stay in the shade; but Piper was already soaked with perspiration. The mosquitoes left welts on her ankles, arms, and neck, so she probably looked like a smallpox victim.

She’d finally gotten some alone time with Jason, and this was how they spent it.

She was irritated with Jason for having mentioned Hera, but she knew she shouldn’t blame him. Maybe she was just irritated with him in general. Ever since Camp Jupiter, she’d been carrying around a lot of worry and resentment.

She wondered what Hercules had wanted to tell her about the sons of Zeus. They couldn’t be trusted? They were under too much pressure? Piper tried to imagine Jason becoming a god when he died, standing on some beach guarding the gates to an ocean long after Piper and everyone else he knew in his mortal life were dead.

She wondered if Hercules had ever been as positive as Jason—more upbeat, confident, quick to comfort. It was hard to picture.

As they hiked down into the next valley, Piper wondered what was happening back on the Argo II. She was tempted to send an Iris-message, but Hercules had warned them not to contact their friends. She hoped Annabeth could guess what was going on and didn’t try to send another party ashore. Piper wasn’t sure what Hercules would do if he were bothered further. She imagined Coach Hedge getting impatient and aiming a ballista at the man in purple, or eidolons possessing the crew and forcing them to commit suicide-by-Hercules.

Piper shuddered. She didn’t know what time it was, but the sun was already starting to sink. How had the day passed so quickly? She would have welcomed sundown for the cooler temperatures, except it was also their deadline. A cool night breeze wouldn’t mean much if they were dead. Besides, tomorrow was July 1, the Kalends of July. If their information was correct, it would be Nico di Angelo’s last day of life, and the day Rome was destroyed.

“Stop,” Jason said.

Piper wasn’t sure what was wrong. Then she realized she could hear running water up ahead. They crept through the trees and found themselves on the bank of a river. It was maybe forty feet wide but only a few inches deep, a silver sheet of water racing over a smooth bed of stones. A few yards downstream, the rapids plunged into a dark blue swimming hole.

Something about the river bothered her. The cicadas in the trees had gone quiet. No birds were chirping. It was as if the water was giving a lecture and would only allow its own voice.

But the more Piper listened, the more inviting the river seemed. She wanted to take a drink. Maybe she should take off her shoes. Her feet could really use a soak. And that swimming hole…it would be so nice to jump in with Jason and relax in the shade of the trees, floating in the nice cool water. So romantic.

Piper shook herself. These thoughts weren’t hers. Something was wrong. It almost felt like the river was charmspeaking.

Jason sat on a rock and started taking off his shoes. He grinned at the swimming hole like he couldn’t wait to get in.

“Cut it out!” Piper yelled at the river.

Jason looked startled. “Cut what out?”

“Not you,” Piper said. “Him.”

She felt silly pointing at the water, but she was certain it was working some sort of magic, swaying their feelings.

Just when she thought she had lost it and Jason would tell her so, the river spoke: Forgive me. Singing is one of the few pleasures I have left.

A figure emerged from the swimming hole as if rising on an elevator.

Piper’s shoulders tensed. It was the creature she’d seen in her knife blade, the bull with the human face. His skin was as blue as the water. His hooves levitated on the river’s surface. At the top of his bovine neck was the head of a man with short curly black hair, a beard done in ringlets Ancient Greek style, deep, mournful eyes behind bifocal glasses, and a mouth that seemed set in a permanent pout. Sprouting from the left side of his head was a single bull’s horn—a curved black-and-white one like warriors might turn into drinking cups. The imbalance made his head tilt to the left, so that he looked like he was trying to get water out of his ear.

“Hello,” he said sadly. “Come to kill me, I suppose.”

Jason put his shoes back on and stood slowly. “Um, well—”

“No!” Piper intervened. “I’m sorry. This is embarrassing. We didn’t want to bother you, but Hercules sent us.”

“Hercules!” The bull-man sighed. His hooves pawed the water as if ready to charge. “To me, he’ll always be Heracles. That’s his Greek name, you know: the glory of Hera.”

“Funny name,” Jason said. “Since he hates her.”

“Indeed,” the bull-man said. “Perhaps that’s why he didn’t protest when the Romans renamed him Hercules. Of course, that’s the name most people know him by…his brand, if you will. Hercules is nothing if not image-conscious.”

The bull-man spoke with bitterness but familiarity, as if Hercules was an old friend who had lost his way.

“You’re Achelous?” Piper asked.

The bull-man bent his front legs and lowered his head in a bow, which Piper found both sweet and a little sad. “At your service. River god extraordinaire. Once the spirit of the mightiest river in Greece. Now sentenced to dwell here, on the opposite side of the island from my old enemy. Oh, the gods are cruel! But whether they put us so close together to punish me or Hercules, I have never been sure.”

Piper wasn’t sure what he meant, but the background noise of the river was invading her mind again—reminding her how hot and thirsty she felt, how pleasant a nice swim would be. She tried to focus.

“I’m Piper,” she said. “This is Jason. We don’t want to fight. It’s just that Heracles—Hercules—whoever he is, got mad at us and sent us here.”

She explained about their quest to the ancient lands to stop the giants from waking Gaea. She described how their team of Greeks and Romans had come together, and how Hercules had thrown a temper tantrum when he found out Hera was behind it.

Achelous kept tipping his head to the left, so Piper wasn’t sure if he was dozing off or dealing with one-horn fatigue.

When she was done, Achelous regarded her as if she were developing a regrettable skin rash. “Ah, my dear…the legends are true, you know. The spirits, the water cannibals.”

Piper had to fight back a whimper. She hadn’t told Achelous anything about that. “H-how—?”

“River gods know many things,” he said. “Alas, you are focusing on the wrong story. If you had made it to Rome, the story of the flood would have served you better.”

“Piper?” Jason asked. “What’s he talking about?”

Her thoughts were suddenly as jumbled as kaleidoscope glass. The story of the flood…If you had made it to Rome.

“I—I’m not sure,” she said, though the mention of a flood story rang a distant bell. “Achelous, I don’t understand—”

“No, you don’t,” the river god sympathized. “Poor thing. Another girl stuck with a son of Zeus.”

“Wait a minute,” Jason said. “It’s Jupiter, actually. And how does that make her a poor thing?”

Achelous ignored him. “My girl, do you know the cause of my fight with Hercules?”

“It was over a woman,” Piper recalled. “Deianira?”

“Yes.” Achelous heaved a sigh. “And do you know what happened to her?”

“Uh…” Piper glanced at Jason.

He took out his guidebook and began flipping through pages. “It doesn’t really—”

Achelous snorted indignantly. “What is that?”

Jason blinked. “Just…The Hercules Guide to Mare Nostrum. He gave us the guidebook so—”

“That is not a book,” Achelous insisted. “He gave you that just to get under my skin, didn’t he? He knows I hate those things.”

“You hate…books?” Piper asked.

“Bah!” Achelous’s face flushed, turning his blue skin eggplant purple. “That’s not a book.”

He pawed the water. A scroll shot from the river like a miniature rocket and landed in front of him. He nudged it open with his hooves. The weathered yellow parchment unfurled, covered with faded Latin script and elaborate hand-drawn pictures.

“This is a book!” Achelous said. “Oh, the smell of sheepskin! The elegant feel of the scroll unrolling beneath my hooves. You simply can’t duplicate it in something like that.”

He nodded indignantly at the guidebook in Jason’s hand. “You young folks today and your newfangled gadgets. Bound pages. Little compact squares of text that are not hoof-friendly. That’s a bound book, a b-book, if you must. But it’s not a traditional book. It’ll never replace the good old-fashioned scroll!”

“Um, I’ll just put this away now.” Jason slipped the guidebook in his back pocket the way he might holster a dangerous weapon.

Achelous seemed to calm down a little, which was a relief to Piper. She didn’t need to get run over by a one-horned bull with a scroll obsession.

“Now,” Achelous said, tapping a picture on his scroll. “This is Deianira.”

Piper knelt down to look. The hand-painted portrait was small, but she could tell the woman had been very beautiful, with long dark hair, dark eyes, and a playful smile that probably drove guys crazy.

“Princess of Calydon,” the river god said mournfully. “She was promised to me, until Hercules butted in. He insisted on combat.”

“And he broke off your horn?” Jason guessed.

“Yes,” Achelous said. “I could never forgive him for that. Horribly uncomfortable, having only one horn. But the situation was worse for poor Deianira. She could have had a long, happy life married to me.”

“A man-headed bull,” Piper said, “who lives in a river.”

“Exactly,” Achelous agreed. “It seems impossible she would refuse, eh? Instead, she went off with Hercules. She picked the handsome, flashy hero over the good, faithful husband who would have treated her well. What happened next? Well, she should have known. Hercules was much too wrapped up in his own problems to be a good husband. He had already murdered one wife, you know. Hera cursed him, so he flew into a rage and killed his entire family. Horrible business. That’s why he had to do those twelve labors as penance.”

Piper felt appalled. “Wait…Hera made him crazy, and Hercules had to do the penance?”

Achelous shrugged. “The Olympians never seem to pay for their crimes. And Hera has always hated the sons of Zeus…or Jupiter.” He glanced distrustfully at Jason. “At any rate, my poor Deianira had a tragic end. She became jealous of Hercules’s many affairs. He gallivanted all over the world, you see, just like his father Zeus, flirting with every woman he met. Finally Deianira got so desperate she listened to bad advice. A crafty centaur named Nessus told her that if she wanted Hercules to be faithful forever, she should spread some centaur blood on the inside of Hercules’s favorite shirt. Unfortunately Nessus was lying because he wanted revenge on Hercules. Deianira followed his instructions, but instead of making Hercules a faithful husband—”

“Centaur blood is like acid,” Jason said.

“Yes,” Achelous said. “Hercules died a painful death. When Deianira realized what she’d done, she…” The river god drew a line across his neck.

“That’s awful,” Piper said.

“And the moral, my dear?” Achelous said. “Beware the sons of Zeus.”

Piper couldn’t look at her boyfriend. She wasn’t sure she could mask the uneasiness in her eyes. Jason would never be like Hercules. But the story played into all her fears. Hera had manipulated their relationship, just as she had manipulated Hercules. Piper wanted to believe that Jason could never go into a murderous frenzy like Hercules had. Then again, only four days ago he had been controlled by an eidolon and almost killed Percy Jackson.

“Hercules is a god now,” Achelous said. “He married Hebe, the youth goddess, but still he is rarely at home. He dwells here on this island, guarding those silly pillars. He says Zeus makes him do this, but I think he prefers being here to Mount Olympus, nursing his bitterness and mourning his mortal life. My presence reminds him of his failures—especially the woman who finally killed him. And his presence reminds me of poor Deianira, who could have been my wife.”

The bull-man tapped the scroll, which rolled itself up and sank into the water.

“Hercules wants my other horn in order to humiliate me,” Achelous said. “Perhaps it would make him feel better about himself, knowing that I’m miserable too. Besides, the horn would become a cornucopia. Good food and drink would flow from it, just as my power causes the river to flow. No doubt Hercules would keep the cornucopia for himself. It would be a tragedy and a waste.”

Piper suspected the noise of the river and the drowsy sound of Achelous’s voice were still affecting her thoughts, but she couldn’t help agreeing with the river god. She was starting to hate Hercules. This poor bull-man seemed so sad and lonely.

Jason stirred. “I’m sorry, Achelous. Honestly, you’ve gotten a bum deal. But maybe…well, without the other horn, you might not be so lopsided. It might feel better.”

“Jason!” Piper protested.

Jason held up his hands. “Just a thought. Besides, I don’t see that we have many choices. If Hercules doesn’t get that horn, he’ll kill us and our friends.”

“He’s right,” Achelous said. “You have no choice. Which is why I hope you’ll forgive me.”

Piper frowned. The river god sounded so heartbroken, she wanted to pat his head. “Forgive you for what?”

“I have no choice either,” Achelous said. “I have to stop you.”

The river exploded, and a wall of water crashed over Piper.

THE CURRENT GRABBED HER LIKE A FIST and pulled her into the deep. Struggling was useless. She clamped her mouth shut, forcing herself not to inhale, but she could barely keep from panicking. She couldn’t see anything but a torrent of bubbles. She could only hear her own thrashing and the dull roar of the rapids.

She’d just about decided this was how she would die: drowning in a swimming hole on an island that didn’t exist. Then, as suddenly as she’d been pulled under, she was thrust to the surface. She found herself at the center of a whirlpool, able to breathe but unable to break free.

A few yards away, Jason broke the surface and gasped, his sword in one hand. He swung wildly, but there was nothing to attack.

Twenty feet to Piper’s right, Achelous rose from the water. “I’m really sorry about this,” he said.

Jason lunged toward him, summoning the winds to lift him out of the river, but Achelous was quicker and more powerful. A curl of water slammed into Jason and sent him under once more.

“Stop it!” Piper screamed.

Using charmspeak wasn’t easy when she was floundering in a whirlpool, but she got Achelous’s attention.

“I’m afraid I can’t stop,” said the river god. “I can’t let Hercules have my other horn. It would be mortifying.”

“There’s another way!” Piper said. “You don’t have to kill us!”

Jason clawed his way to the surface again. A miniature storm cloud formed over his head. Thunder boomed.

“None of that, son of Jupiter,” Achelous chided. “If you call lightning, you’ll just electrocute your girlfriend.”

The water pulled Jason under again.

“Let him go!” Piper charged her voice with all the persuasiveness she could muster. “I promise I won’t let Hercules get the horn!”

Achelous hesitated. He cantered over to her, his head tilting to the left. “I believe you mean that.”

“I do!” Piper promised. “Hercules is despicable. But, please, first let my friend go.”

The water churned where Jason had gone under. Piper wanted to scream. How much longer could he hold his breath?

Achelous looked down at her through his bifocals. His expression softened. “I see. You would be my Deianira. You would be my bride to compensate for my loss.”

“What?” Piper wasn’t sure if she’d heard him right. The whirlpool was literally making her head spin. “Uh, actually I was thinking—”

“Oh, I understand,” Achelous said. “You were too modest to suggest this in front of your boyfriend. You are right, of course. I would treat you much better than a son of Zeus would. I could make things right after all these centuries. I could not save Deianira, but I could save you.”

Had it been thirty seconds now? A minute? Jason couldn’t hold out much longer.

“You would have to let your friends die,” Achelous continued. “Hercules would be angry, but I can protect you from him. We could be quite happy together. Let’s start by letting that Jason fellow drown, eh?”

Piper could barely hold it together, but she had to concentrate. She masked her fear and her anger. She was a child of Aphrodite. She had to use the tools she was given.

She smiled as sweetly as she could and raised her arms. “Lift me up, please.”

Achelous’s face brightened. He grabbed Piper’s hands and pulled her out of the whirlpool.

She’d never ridden a bull before, but she’d practiced bareback pegasus riding at Camp Half-Blood, and she remembered what to do. She used her momentum, swinging one leg over Achelous’s back. Then she locked her ankles around his neck, wrapped one arm around his throat, and drew her knife with the other. She pressed the blade under the river god’s chin.

“Let—Jason—go.” She put all her force into the command. “Now!”

Piper realized there were many flaws in her plan. The river god might simply dissolve into water. Or he could pull her under and wait for her to drown. But apparently her charmspeak worked. Or maybe Achelous was just too surprised to think straight. He probably wasn’t used to pretty girls threatening to cut his throat.

Jason shot out of the water like a human cannonball. He broke through the branches of an olive tree and tumbled onto the grass. That couldn’t have felt good, but he struggled to his feet, gasping and coughing. He raised his sword, and the dark clouds thickened over the river.

Piper shot him a warning look: Not yet. She still had to get out of this river without drowning or getting electrocuted.

Achelous arched his back as if contemplating a trick. Piper pressed the knife harder against his throat.

“Be a good bull,” she warned.

“You promised,” Achelous said through gritted teeth. “You promised Hercules wouldn’t get my horn.”

“And he won’t,” Piper said. “But I will.”

She raised her knife and slashed off the god’s horn. The Celestial bronze cut through the base like it was wet clay. Achelous bellowed in rage. Before he could recover, Piper stood up on his back. With the horn in one hand and her dagger in the other, she leaped for the shore.

“Jason!” she yelled.

Thank the gods, he understood. A gust of wind caught her and carried her safely over the bank. Piper hit the ground rolling as the hairs on her neck stood up. A metallic smell filled the air. She turned toward the river in time to be blinded.

BOOM!Lightning stirred the water into a boiling cauldron, steaming and hissing with electricity. Piper blinked the yellow spots out of her eyes as the god Achelous wailed and dissolved beneath the surface. His horrified expression seemed to be asking: How could you?

“Jason, run!” She was still dizzy and sick with fear, but she and Jason crashed through the woods.

As she climbed the hill, clasping the bull’s horn to her chest, Piper realized she was sobbing—though she wasn’t sure if it was from fear, or relief, or shame for what she’d done to the old river god.

They didn’t slow down until they reached the crest of the hill.

Piper felt silly, but she kept breaking down and crying as she told Jason what had happened while he was struggling underwater.

“Piper, you had no choice.” He put his hand on her shoulder. “You saved my life.”

She wiped her eyes and tried to control herself. The sun was nearing the horizon. They had to get back to Hercules quickly, or their friends would die.

“Achelous forced your hand,” Jason continued. “Besides, I doubt that lightning bolt killed him. He’s an ancient god. You’d have to destroy his river to destroy him. And he can live without a horn. If you had to lie about not giving it to Hercules, well—”

“I wasn’t lying.”

Jason stared at her. “Pipes…we don’t have a choice. Hercules will kill—”

“Hercules doesn’t deserve this.” Piper wasn’t sure where this rage was coming from, but she had never felt more certain of anything in her life.

Hercules was a bitter, selfish jerk. He’d hurt too many people, and he wanted to keep on hurting them. Maybe he’d had some bad breaks. Maybe the gods had kicked him around. But that didn’t excuse it. A hero couldn’t control the gods, but he should be able to control himself.

Jason would never be like that. He would never blame others for his problems or make a grudge more important than doing the right thing.

Piper was not going to repeat Deianira’s story. She wasn’t going to go along with what Hercules wanted just because he was handsome and strong and scary. He couldn’t get his way this time—not after threatening their lives and sending them to make Achelous miserable for the sake of spiting Hera. Hercules didn’t deserve a horn of plenty. Piper was going to put him in his place.

“I have a plan,” she said.

She told Jason what to do. She didn’t even realize she was using charmspeak until his eyes glazed over.

“Whatever you say,” he promised. Then he blinked a few times. “We’re going to die, but I’m in.”

Hercules was waiting right where they’d left him. He was staring at the Argo II, docked between the pillars as the sun set behind it. The ship looked okay, but Piper’s plan had started to feel insane to her.

Too late to reconsider. She’d already sent an Iris-message to Leo. Jason was prepared. And, seeing Hercules again, she felt more certain than ever she couldn’t give him what he wanted.

Hercules didn’t exactly brighten when he saw Piper carrying the bull’s horn, but his scowl lines lessened.

“Good,” he said. “You got it. In that case, you are free to go.”

Piper glanced at Jason. “You heard him. He gave us permission.” She turned back to the god. “That means our ship will be able to pass into the Mediterranean?”

“Yes, yes.” Hercules snapped his fingers. “Now, the horn.”

“No,” Piper said.

The god frowned. “Excuse me?”

She raised the cornucopia. Since she’d cut it from Achelous’s head, the horn had hollowed out, becoming smooth and dark on the inside. It didn’t appear magical, but Piper was counting on its power.

“Achelous was right,” she said. “You’re his curse as much as he is yours. You’re a sorry excuse for a hero.”

Hercules stared at her as if she were speaking in Japanese. “You realize I could kill you with a flick of my finger,” he said. “I could throw my club at your ship and cut straight through its hull. I could—”

“You could shut up,” Jason said. He drew his sword. “Maybe Zeus is different from Jupiter. Because I wouldn’t put up with any brother who acts like you.”

The veins on Hercules’s neck turned as purple as his robes. “You would not be the first demigod I’ve killed.”

“Jason is better than you,” Piper said. “But don’t worry. We’re not going to fight you. We’re going to leave this island with the horn. You don’t deserve it as a prize. I’m going to keep it, to remind me of what not to be like as a demigod, and to remind me of poor Achelous and Deianira.”

The god’s nostrils flared. “Do not mention that name! You can’t seriously think I’m worried about your puny boyfriend. No one is stronger than me.”

“I didn’t say stronger,” Piper corrected. “I said he’s better.”

Piper pointed the mouth of the horn at Hercules. She let go of the resentment and doubt and anger she’d been harboring since Camp Jupiter. She concentrated on all the good things she’d shared with Jason Grace: soaring upward in the Grand Canyon, walking on the beach at Camp Half-Blood, holding hands at the sing-along and watching the stars, sitting by the strawberry fields together on lazy afternoons and listening to the satyrs play their pipes.

She thought about a future when the giants had been defeated, Gaea was asleep, and they would live happily together—no jealousy, no monsters left to battle. She filled her heart with those thoughts, and she felt the cornucopia grow warm.

The horn blasted forth a flood of food as powerful as Achelous’s river. A torrent of fresh fruit, baked goods, and smoked hams completely buried Hercules. Piper didn’t understand how all that stuff could fit through the entrance of the horn, but she thought the hams were especially appropriate.

When it had spewed out enough goodies to fill a house, the horn shut itself off. Piper heard Hercules shrieking and struggling somewhere underneath. Apparently even the strongest god in the world could be caught off guard when buried under fresh produce.

“Go!” she told Jason, who’d forgotten his part of the plan and was staring in amazement at the fruit pile. “Go!”

He grabbed Piper’s waist and summoned the wind. They shot away from the island so quickly, Piper almost got whiplash; but it wasn’t a second too soon.

As the island retreated from view, Hercules’s head broke above the mound of goodies. Half a coconut was stuck on his noggin like a war helmet. “Kill!” he bellowed, like he’d had a lot of practice saying it.

Jason touched down on the deck of the Argo II. Thankfully, Leo had done his part. The ship’s oars were already in aerial mode. The anchor was up. Jason summoned a gale so strong, it pushed them into the sky, while Percy sent a ten-foot-tall wave against the shore, knocking Hercules down a second time, in a cascade of seawater and pineapples.

By the time the god regained his feet and started lobbing coconuts at them from far below, the Argo II was already sailing through the clouds above the Mediterranean.

PERCY WAS NOT FEELING THE LOVE.

Bad enough he’d been run out of Atlanta by evil sea gods. Then he had failed to stop a giant shrimp attack on the Argo II. Then the ichthyocentaurs, Chiron’s brothers, hadn’t even wanted to meet him.

After all that, they had arrived at the Pillars of Hercules, and Percy had to stay aboard ship while Jason the Big Shot visited his half brother. Hercules, the most famous demigod of all time, and Percy didn’t get to meet him either.

Okay, sure, from what Piper said afterward, Hercules was a jerk, but still…Percy was getting kind of tired of staying aboard ship and pacing the deck.

The open sea was supposed to be his territory. Percy was supposed to step up, take charge, and keep everybody safe. Instead, all the way across the Atlantic, he’d done pretty much nothing except make small talk with sharks and listen to Coach Hedge sing TV theme songs.

To make matters worse, Annabeth had been distant ever since they had left Charleston. She spent most of her time in her cabin, studying the bronze map she’d retrieved from Fort Sumter, or looking up information on Daedalus’s laptop.

Whenever Percy stopped by to see her, she was so lost in thought that the conversation went something like this:

Percy: “Hey, how’s it going?”

Annabeth: “Uh, no thanks.”

Percy: “Okay…have you eaten anything today?”

Annabeth: “I think Leo is on duty. Ask him.”

Percy: “So, my hair is on fire.”

Annabeth: “Okay. In a while.”

She got like this sometimes. It was one of the challenges of dating an Athena girl. Still, Percy wondered what he had to do to get her attention. He was worried about her after her encounter with the spiders at Fort Sumter, and he didn’t know how to help her, especially if she shut him out.

After leaving the Pillars of Hercules—unscathed except for a few coconuts lodged in the hull’s bronze plating—the ship traveled by air for a few hundred miles.

Percy hoped the ancient lands wouldn’t be as bad as they’d heard. But it was almost like a commercial: You’ll notice the difference immediately!

Several times an hour, something attacked the ship. A flock of flesh-eating Stymphalian birds swooped out of the night sky, and Festus torched them. Storm spirits swirled around the mast, and Jason blasted them with lightning. While Coach Hedge was having dinner on the foredeck, a wild pegasus appeared from nowhere, stampeded over the coach’s enchiladas, and flew off again, leaving cheesy hoof prints all across the deck.

“What was that for?” the coach demanded.

The sight of the pegasus made Percy wish Blackjack were here. He hadn’t seen his friend in days. Tempest and Arion also hadn’t shown themselves. Maybe they didn’t want to venture into the Mediterranean. If so, Percy couldn’t blame them.

Finally around midnight, after the ninth or tenth aerial attack, Jason turned to him. “How about you get some sleep? I’ll keep blasting stuff out of the sky as long as I can. Then we can go by sea for a while, and you can take point.”

Percy wasn’t sure that he’d be able to sleep with the boat rocking through the clouds as it was shaken by angry wind spirits, but Jason’s idea made sense. He went belowdecks and crashed on his bunk.

His nightmares, of course, were anything but restful.

He dreamed he was in a dark cavern. He could only see a few feet in front of him, but the space must have been vast. Water dripped from somewhere nearby, and the sound echoed off distant walls. The way the air moved made Percy suspect the cave’s ceiling was far, far above.

He heard heavy footsteps, and the twin giants Ephialtes and Otis shuffled out of the gloom. Percy could distinguish them only by their hair—Ephialtes had the green locks braided with silver and gold coins; Otis had the purple ponytail braided with…were those firecrackers?

Otherwise they were dressed identically, and their outfits definitely belonged in a nightmare. They wore matching white slacks and gold buccaneer shirts with V-necks that showed way too much chest hair. A dozen sheathed daggers lined their rhinestone belts. Their shoes were open-toed sandals, proving that—yes, indeed—they had snakes for feet. The straps wrapped around the serpents’ necks. Their heads curled up where the toes should be. The snakes flicked their tongues excitedly and turned their gold eyes in every direction, like dogs looking out the window of a car. Maybe it had been a long time since they’d had shoes with a view.

The giants stood in front of Percy, but they paid him no attention. Instead, they gazed up into the darkness.

“We’re here,” Ephialtes announced. Despite his booming voice, his words dissipated in the cavern, echoing until they sounded small and insignificant.

Far above, something answered, “Yes. I can see that. Those outfits are hard to miss.”

The voice made Percy’s stomach drop about six inches. It sounded vaguely female, but not at all human. Each word was a garbled hiss in multiple tones, as if a swarm of African killer bees had learned to speak English in unison.

It wasn’t Gaea. Percy was sure of that. But whatever it was, the twin giants became nervous. They shifted on their snakes and bobbed their heads respectfully.

“Of course, Your Ladyship,” Ephialtes said. “We bring news of—”

“Why are you dressed like that?” asked the thing in the dark. She didn’t seem to be coming any closer, which was fine with Percy.

Ephialtes shot his brother an irritated look. “My brother was supposed to wear something different. Unfortunately—”

“You said I was the knife thrower today,” Otis protested.

“I said I was the knife thrower! You were supposed to be the magician! Ah, forgive me, Your Ladyship. You don’t want to hear us arguing. We came as you requested, to bring you news. The ship is approaching.”

Her Ladyship, whatever she was, made a series of violent hisses like a tire being slashed repeatedly. With a shudder, Percy realized she was laughing.

“How long?” she asked.

“They should land in Rome shortly after daybreak, I think,” Ephialtes said. “Of course, they’ll have to get past the golden boy.”

He sneered, as if the golden boy was not his favorite person.

“I hope they arrive safely,” Her Ladyship said. “It would spoil our fun to have them captured too soon. Are your preparations made?”

“Yes, Your Ladyship.” Otis stepped forward, and the cavern trembled. A crack appeared under Otis’s left snake.

“Careful, you dolt!” Her Ladyship snarled. “Do you want to return to Tartarus the hard way?”

Otis scrambled back, his face slack with terror. Percy realized that the floor, which looked like solid stone, was more like the glacier he’d walked on in Alaska—in some places solid, in other places…not so much. He was glad he weighed nothing in his dreams.

“There is little left holding this place together,” Her Ladyship cautioned. “Except, of course, my own skill. Centuries of Athena’s rage can only be contained so well, and the great Earth Mother churns below us in her sleep. Between those two forces, well…my nest has quite eroded. We must hope this child of Athena proves to be a worthy victim. She may be my last plaything.”

Ephialtes gulped. He kept his eyes on the crack in the floor. “Soon it will not matter, Your Ladyship. Gaea will rise, and we all will be rewarded. You will no longer have to guard this place, or keep your works hidden.”

“Perhaps,” said the voice in the dark. “But I will miss the sweetness of my revenge. We have worked well together over the centuries, have we not?”

The twins bowed. The coins glittered in Ephialtes’s hair, and Percy realized with nauseating certainty that some of them were silver drachma, exactly like the one Annabeth had gotten from her mom.

Annabeth had told him that in each generation, a few children of Athena were sent on the quest to recover the missing Parthenon statue. None had ever succeeded.

We have worked well together over the centuries.…

The giant Ephialtes had centuries’ worth of coins in his braids—hundreds of trophies. Percy pictured Annabeth standing in this dark place alone. He imagined the giant taking that coin she carried and adding it to his collection. Percy wanted to draw his sword and give the giant a haircut starting at the neck, but he was powerless to act. He could only watch.

“Uh, Your Ladyship,” Ephialtes said nervously. “I would remind you that Gaea wishes the girl to be taken alive. You can torment her. Drive her insane. Whatever you wish, of course. But her blood must be spilt on the ancient stones.”

Her Ladyship hissed. “Others could be used for that purpose.”

“Y-yes,” Ephialtes said. “But this girl is preferred. And the boy—the son of Poseidon. You can see why those two would be most suited for the task.”

Percy wasn’t sure what that meant, but he wanted to crack the floor and send these stupid gold-shirted twins down to oblivion. He’d never let Gaea spill his blood for any task—and there was no way he’d let anyone hurt Annabeth.

“We will see,” Her Ladyship grumbled. “Leave me now. Tend to your own preparations. You will have your spectacle. And I…I will work in darkness.”

The dream dissolved, and Percy woke with a start.

Jason was knocking at his open doorway.

“We’ve set down in the water,” he said, looking utterly exhausted. “Your turn.”

Percy didn’t want to, but he woke Annabeth. He figured even Coach Hedge wouldn’t mind their talking after curfew if it meant giving her information that might save her life.

They stood on deck, alone except for Leo, who was still manning the helm. The guy must have been shattered, but he refused to go to sleep.

“I don’t want any more Shrimpzilla surprises,” he insisted.

They’d all tried to convince Leo that the skolopendra attack hadn’t been entirely his fault, but he wouldn’t listen. Percy knew how he felt. Not forgiving himself for mistakes was one of Percy’s biggest talents.

It was about four in the morning. The weather was miserable. The fog was so thick, Percy couldn’t see Festus at the end of the prow, and warm drizzle hung in the air like a bead curtain. As they sailed into twenty-foot swells, the sea heaving underneath them, Percy could hear poor Hazel down in her cabin…also heaving.

Despite all that, Percy was grateful to be back on the water. He preferred it to flying through storm clouds and being attacked by man-eating birds and enchilada-trampling pegasi.

He stood with Annabeth at the forward rail while he told her about his dream.

Percy wasn’t sure how she’d take the news. Her reaction was even more troubling than he anticipated: she didn’t seem surprised.

She peered into the fog. “Percy, you have to promise me something. Don’t tell the others about this dream.”

“Don’t what? Annabeth—”

“What you saw was about the Mark of Athena,” she said. “It won’t help the others to know. It’ll only make them worry, and it’ll make it harder for me to go off on my own.”

“Annabeth, you can’t be serious. That thing in the dark, the big chamber with the crumbling floor—”

“I know.” Her face looked unnaturally pale, and Percy suspected it wasn’t just the fog. “But I have to do this alone.”

Percy swallowed back his anger. He wasn’t sure if he was mad at Annabeth, or his dream, or the entire Greek/Roman world that had endured and shaped human history for five thousand years with one goal in mind: to make Percy Jackson’s life suck as much as possible.

“You know what’s in that cavern,” he guessed. “Does it have to do with spiders?”

“Yes,” she said in a small voice.

“Then how can you even…?” He made himself stop.

Once Annabeth had made up her mind, arguing with her wouldn’t do any good. He remembered the night three and a half years ago, when they’d saved Nico and Bianca di Angelo in Maine. Annabeth had been captured by the Titan Atlas. For a while, Percy wasn’t sure if she was alive or dead. He’d traveled across the country to save her from the Titan. It had been the hardest few days of his life—not just the monsters and the fighting, but the worry.

How could he intentionally let her go now, knowing she was heading into something even more dangerous?

Then it dawned on him: the way he had felt back then, for a few days, was probably how Annabeth had felt for the six months he had been missing with amnesia.

That made him feel guilty, and a little bit selfish, to be standing here arguing with her. She had to go on this quest. The fate of the world might depend on it. But part of him wanted to say: Forget the world. He didn’t want to be without her.

Percy stared into the fog. He couldn’t see anything around them, but he had perfect bearings at sea. He knew their exact latitude and longitude. He knew the depth of the ocean and which way the currents were flowing. He knew the ship’s speed, and could sense no rocks, sandbars, or other natural dangers in their path. Still, being blind was unsettling.

They hadn’t been attacked since they had touched the water, but the sea seemed different. Percy had been in the Atlantic, the Pacific, even the Gulf of Alaska, but this sea felt more ancient and powerful. Percy could sense its layers swirling below him. Every Greek or Roman hero had sailed these waters—from Hercules to Aeneas. Monsters still dwelt in the depths, so deeply wrapped in the Mist that they slept most of the time; but Percy could feel them stirring, responding to the Celestial bronze hull of a Greek trireme and the presence of demigod blood.

They are back, the monsters seemed to say. Finally, fresh blood.

“We’re not far from the Italian coast,” Percy said, mostly to break the silence. “Maybe a hundred nautical miles to the mouth of the Tiber.”

“Good,” Annabeth said. “By daybreak, we should—”

“Stop.” Percy’s skin felt washed with ice. “We have to stop.”

“Why?” Annabeth asked.

“Leo, stop!” he yelled.

Too late. The other boat appeared out of the fog and rammed them head-on. In that split second, Percy registered random details: another trireme; black sails painted with a gorgon’s head; hulking warriors, not quite human, crowded at the front of the boat in Greek armor, swords and spears ready; and a bronze ram at water level, slamming against the hull of the Argo II.

Annabeth and Percy were almost thrown overboard.

Festus blew fire, sending a dozen very surprised warriors screaming and diving into the sea, but more swarmed aboard the Argo II. Grappling lines wrapped around the rails and the mast, digging iron claws into the hull’s planks.

By the time Percy had recovered his wits, the enemy was everywhere. He couldn’t see well through the fog and the dark, but the invaders seemed to be humanlike dolphins, or dolphinlike humans. Some had gray snouts. Others held their swords in stunted flippers. Some waddled on legs partially fused together, while others had flippers for feet, which reminded Percy of clown shoes.

Leo sounded the alarm bell. He made a dash for the nearest ballista but went down under a pile of chattering dolphin warriors.

Annabeth and Percy stood back-to-back, as they’d done many times before, their weapons drawn. Percy tried to summon the waves, hoping he could push the ships apart or even capsize the enemy vessel, but nothing happened. It almost felt like something was pushing against his will, wresting the sea from his control.

He raised Riptide, ready to fight, but they were hopelessly outnumbered. Several dozen warriors lowered their spears and made a ring around them, wisely keeping out of striking distance of Percy’s sword. The dolphin-men opened their snouts and made whistling, popping noises. Percy had never considered just how vicious dolphin teeth looked.

He tried to think. Maybe he could break out of the circle and destroy a few invaders, but not without the others skewering him and Annabeth.

At least the warriors didn’t seem interested in killing them immediately. They kept Percy and Annabeth contained while more of their comrades flooded belowdecks and secured the hull. Percy could hear them breaking down the cabin doors, scuffling with his friends. Even if the other demigods hadn’t been fast asleep, they wouldn’t have stood a chance against so many.

Leo was dragged across the deck, half-conscious and groaning, and dumped on a pile of ropes. Below, the sounds of fighting tapered off. Either the others had been subdued or…or Percy refused to think about it.

On one side of the ring of spears, the dolphin warriors parted to let someone through. He appeared to be fully human, but from the way the dolphins fell back before him, he was clearly the leader. He was dressed in Greek combat armor—sandals, kilt, and greaves, a breastplate decorated with elaborate sea monster designs—and everything he wore was gold. Even his sword, a Greek blade like Riptide, was gold instead of bronze.

The golden boy, Percy thought, remembering his dream. They’ll have to get past the golden boy.

What really made Percy nervous was the guy’s helmet. His visor was a full face mask fashioned like a gorgon’s head—curved tusks, horrible features pinched into a snarl, and golden snake hair curling around the face. Percy had met gorgons before. The likeness was good—a little too good for his taste.

Annabeth turned so she was shoulder to shoulder with Percy. He wanted to put his arm around her protectively, but he doubted she’d appreciate the gesture, and he didn’t want to give this golden guy any indication that Annabeth was his girlfriend. No sense giving the enemy more leverage than they already had.

“Who are you?” Percy demanded. “What do you want?”

The golden warrior chuckled. With a flick of his blade, faster than Percy could follow, he smacked Riptide out of Percy’s hand and sent it flying into the sea.

He might as well have thrown Percy’s lungs into the sea, because suddenly Percy couldn’t breathe. He’d never been disarmed so easily.

“Hello, brother.” The golden warrior’s voice was rich and velvety, with an exotic accent—Middle Eastern, maybe—that seemed vaguely familiar. “Always happy to rob a fellow son of Poseidon. I am Chrysaor, the Golden Sword. As for what I want…” He turned his metal mask toward Annabeth. “Well, that’s easy. I want everything you have.”

PERCY’S HEART DID JUMPING JACKS while Chrysaor walked back and forth, inspecting them like prized cattle. A dozen of his dolphin-man warriors stayed in a ring around them, spears leveled at Percy’s chest, while dozens more ransacked the ship, banging and crashing around belowdecks. One carried a box of ambrosia up the stairs. Another carried an armful of ballista bolts and a crate of Greek fire.

“Careful with that!” Annabeth warned. “It’ll blow up both our ships.”

“Ha!” Chrysaor said. “We know all about Greek fire, girl. Don’t worry. We’ve been looting and pillaging ships on the Mare Nostrum for eons.”

“Your accent sounds familiar,” Percy said. “Have we met?”

“I haven’t had the pleasure.” Chrysaor’s golden gorgon mask snarled at him, though it was impossible to tell what his real expression might be underneath. “But I’ve heard all about you, Percy Jackson. Oh, yes, the young man who saved Olympus. And his faithful sidekick, Annabeth Chase.”

“I’m nobody’s sidekick,” Annabeth growled. “And, Percy, his accent sounds familiar because he sounds like his mother. We killed her in New Jersey.”

Percy frowned. “I’m pretty sure that accent isn’t New Jersey. Who’s his—? Oh.”

It all fell into place. Aunty Em’s Garden Gnome Emporium—the lair of Medusa. She’d talked with that same accent, at least until Percy had cut off her head.

“Medusa is your mom?” he asked. “Dude, that sucks for you.”

Judging from the sound in Chrysaor’s throat, he was now snarling under the mask, too.

“You are as arrogant as the first Perseus,” Chrysaor said. “But, yes, Percy Jackson. Poseidon was my father. Medusa was my mother. After Medusa was changed into a monster by that so-called goddess of wisdom…” The golden mask turned on Annabeth. “That would be your mother, I believe…Medusa’s two children were trapped inside her, unable to be born. When the original Perseus cut off Medusa’s head—”

“Two children sprang out,” Annabeth remembered. “Pegasus and you.”

Percy blinked. “So your brother is a winged horse. But you’re also my half brother, which means all the flying horses in the world are my…You know what? Let’s forget it.”

He’d learned years ago it was better not to dwell too much on who was related to whom on the godly side of things. After Tyson the Cyclops adopted him as a brother, Percy decided that that was about as far as he wanted to extend the family.

“But if you’re Medusa’s kid,” he said, “why haven’t I ever heard of you?”

Chrysaor sighed in exasperation. “When your brother is Pegasus, you get used to being forgotten. Oh, look, a winged horse! Does anyone care about me? No!” He raised the tip of his blade to Percy’s eyes. “But don’t underestimate me. My name means the Golden Sword for a reason.”

“Imperial gold?” Percy guessed.

“Bah! Enchanted gold, yes. Later on, the Romans called it Imperial gold, but I was the first to ever wield such a blade. I should have been the most famous hero of all time! Since the legend-tellers decided to ignore me, I became a villain instead. I resolved to put my heritage to use. As the son of Medusa, I would inspire terror. As the son of Poseidon, I would rule the seas!”

“You became a pirate,” Annabeth summed up.

Chrysaor spread his arms, which was fine with Percy since it got the sword point away from his eyes.

“The best pirate,” Chrysaor said. “I’ve sailed these waters for centuries, waylaying any demigods foolish enough to explore the Mare Nostrum. This is my territory now. And all you have is mine.”

One of the dolphin warriors dragged Coach Hedge up from below.

“Let me go, you tuna fish!” Hedge bellowed. He tried to kick the warrior, but his hoof clanged off his captor’s armor. Judging from the hoof-shaped prints in the dolphin’s breastplate and helmet, the coach had already made several attempts.

“Ah, a satyr,” Chrysaor mused. “A little old and stringy, but Cyclopes will pay well for a morsel like him. Chain him up.”

“I’m nobody’s goat meat!” Hedge protested.

“Gag him as well,” Chrysaor decided.

“Why you gilded little—” Hedge’s insult was cut short when the dolphin put a greasy wad of canvas in his mouth. Soon the coach was trussed like a rodeo calf and dumped with the other loot—crates of food, extra weapons, even the magical ice chest from the mess hall.

“You can’t do this!” Annabeth shouted.

Chrysaor’s laughter reverberated inside his gold face mask. Percy wondered if he was horribly disfigured under there, or if his gaze could petrify people the way his mother’s could.

“I can do anything I want,” Chrysaor said. “My warriors have been trained to perfection. They are vicious, cutthroat—”

“Dolphins,” Percy noted.

Chrysaor shrugged. “Yes. So? They had some bad luck a few millennia ago, kidnapped the wrong person. Some of their crew got turned completely into dolphins. Others went mad. But these…these survived as hybrid creatures. When I found them under the sea and offered them a new life, they became my loyal crew. They fear nothing!”

One of the warriors chattered at him nervously.

“Yes, yes,” Chrysaor growled. “They fear one thing, but it hardly matters. He’s not here.”

An idea began tickling at the base of Percy’s skull. Before he could pursue it, more dolphin warriors climbed the stairs, hauling up the rest of his friends. Jason was unconscious. Judging from the new bruises on his face, he’d tried to fight. Hazel and Piper were bound hand and foot. Piper had a gag in her mouth, so apparently the dolphins had discovered she could charmspeak. Frank was the only one missing, though two of the dolphins had bee stings covering their faces.

Could Frank actually turn into a swarm of bees? Percy hoped so. If he was free aboard the ship somewhere, that could be an advantage, assuming Percy could figure out how to communicate with him.

“Excellent!” Chrysaor gloated. He directed his warriors to dump Jason by the crossbows. Then he examined the girls like they were Christmas presents, which made Percy grit his teeth.

“The boy is no use to me,” Chrysaor said. “But we have an understanding with the witch Circe. She will buy the women—either as slaves or trainees, depending on their skill. But not you, lovely Annabeth.”

Annabeth recoiled. “You are not taking me anywhere.”

Percy’s hand crept to his pocket. His pen had appeared back in his jeans. He only needed a moment’s distraction to draw his sword. Maybe if he could take down Chrysaor quickly, his crew would panic.

He wished he knew something about Chrysaor’s weaknesses. Usually Annabeth provided him with information like that, but apparently Chrysaor didn’t have any legends, so they were both in the dark.

The golden warrior tutted. “Oh, sadly, Annabeth, you will not be staying with me. I would love that. But you and your friend Percy are spoken for. A certain goddess is paying a high bounty for your capture—alive, if possible, though she didn’t say you had to be unharmed.”

At that moment, Piper caused the disturbance they needed. She wailed so loudly it could be heard through her gag. Then she fainted against the nearest guard, knocking him over. Hazel got the idea and crumpled to the deck, kicking her legs and thrashing like she was having a fit.

Percy drew Riptide and lashed out. The blade should have gone straight through Chrysaor’s neck, but the golden warrior was unbelievably fast. He dodged and parried as the dolphin warriors backed up, guarding the other captives while giving their captain room to battle. They chattered and squeaked, egging him on, and Percy got the sinking suspicion the crew was used to this sort of entertainment. They didn’t feel their leader was in any sort of danger.

Percy hadn’t crossed swords with an opponent like this since…well, since he’d battled the war god Ares. Chrysaor was that good. Many of Percy’s powers had gotten stronger over the years, but now, too late, Percy realized that swordplay wasn’t one of them.

He was rusty—at least against an adversary like Chrysaor.

They battled back and forth, thrusting and parrying. Without meaning to, Percy heard the voice of Luke Castellan, his first sword-fighting mentor at Camp Half-Blood, throwing out suggestions. But it didn’t help.

The golden gorgon mask was too unnerving. The warm fog, the slick deck boards, the chattering of the warriors—none of it helped. And in the corner of his eye, Percy could see one of the dolphin-men holding a knife at Annabeth’s throat in case she tried anything tricky.

He feinted and thrust at Chrysaor’s gut, but Chrysaor anticipated the move. He knocked Percy’s sword out of his hand again, and once more Riptide flew into the sea.

Chrysaor laughed easily. He wasn’t even winded. He pressed the tip of his golden sword against Percy’s sternum.

“A good try,” said the pirate. “But now you’ll be chained and transported to Gaea’s minions. They are quite eager to spill your blood and wake the goddess.”

NOTHING LIKE TOTAL FAILURE to generate great ideas.

As Percy stood there, disarmed and outmatched, the plan formed in his head. He was so used to Annabeth providing Greek legend information that he was kind of stunned to actually remember something useful, but he had to act fast. He couldn’t let anything happen to his friends. He wasn’t going to lose Annabeth—not again.

Chrysaor couldn’t be beat. At least not in single combat. But without his crew…maybe then he could be overwhelmed if enough demigods attacked him at once.

How to deal with Chrysaor’s crew? Percy put the pieces together: the pirates had been turned into dolphin-men millennia ago when they had kidnapped the wrong person. Percy knew that story. Heck, the wrong person in question had threatened to turn him into a dolphin. And when Chrysaor said the crew wasn’t afraid of anything, one of the dolphins had nervously corrected him. Yes, Chrysaor said. But he’s not here.

Percy glanced toward the stern and spotted Frank, in human form, peeking out from behind a ballista, waiting. Percy resisted the urge to smile. The big guy claimed to be clumsy and useless, but he always seemed to be in exactly the right place when Percy needed him.

The girls…Frank…the ice chest.

It was a crazy idea. But, as usual, that’s all Percy had.

“Fine!” Percy shouted, so loudly that he got everyone’s attention. “Take us away, if our captain will let you.”

Chrysaor turned his golden mask. “What captain? My men searched the ship. There is no one else.”

Percy raised his hands dramatically. “The god appears only when he wishes. But he is our leader. He runs our camp for demigods. Doesn’t he, Annabeth?”

Annabeth was quick. “Yes!” She nodded enthusiastically. “Mr. D! The great Dionysus!”

A ripple of uneasiness passed through the dolphin-men. One dropped his sword.

“Stand fast!” Chrysaor bellowed. “There is no god on this ship. They are trying to scare you.”

“You should be scared!” Percy looked at the pirate crew with sympathy. “Dionysus will be severely cranky with you for having delayed our voyage. He will punish all of us. Didn’t you notice the girls falling into the wine god’s madness?”

Hazel and Piper had stopped the shaking fits. They were sitting on the deck, staring at Percy, but when he glared at them pointedly, they started hamming it up again, trembling and flopping around like fish. The dolphin-men fell over themselves trying to get away from their captives.

“Fakes!” Chrysaor roared. “Shut up, Percy Jackson. Your camp director is not here. He was recalled to Olympus. This is common knowledge.”

“So you admit Dionysus is our director!” Percy said.

“He was,” Chrysaor corrected. “Everyone knows that.”

Percy gestured at the golden warrior like he’d just betrayed himself. “You see? We are doomed. If you don’t believe me, let’s check the ice chest!”

Percy stormed over to the magical cooler. No one tried to stop him. He knocked open the lid and rummaged through the ice. There had to be one. Please. He was rewarded with a silver-and-red can of soda. He brandished it at the dolphin warriors as if spraying them with bug repellent.

“Behold!” Percy shouted. “The god’s chosen beverage. Tremble before the horror of Diet Coke!”

The dolphin-men began to panic. They were on the edge of retreat. Percy could feel it.

“The god will take your ship,” Percy warned. “He will finish your transformation into dolphins, or make you insane, or transform you into insane dolphins! Your only hope is to swim away now, quickly!”

“Ridiculous!” Chrysaor’s voice turned shrill. He didn’t seem sure where to level his sword—at Percy or his own crew.

“Save yourselves!” Percy warned. “It is too late for us!”

Then he gasped and pointed to the spot where Frank was hiding. “Oh, no! Frank is turning into a crazy dolphin!”

Nothing happened.

“I said,” Percy repeated, “Frank is turning into a crazy dolphin!”

Frank stumbled out of nowhere, making a big show of grabbing his throat. “Oh, no,” he said, like he was reading from a teleprompter. “I am turning into a crazy dolphin.”

He began to change, his nose elongating into a snout, his skin becoming sleek and gray. He fell to the deck as a dolphin, his tail thumping against the boards.

The pirate crew disbanded in terror, chattering and clicking as they dropped their weapons, forgot the captives, ignored Chrysaor’s orders, and jumped overboard. In the confusion, Annabeth moved quickly to cut the bonds on Hazel, Piper, and Coach Hedge.

Within seconds, Chrysaor was alone and surrounded. Percy and his friends had no weapons except for Annabeth’s knife and Hedge’s hooves, but the murderous looks on their faces evidently convinced the golden warrior he was doomed.

He backed to the edge of the rail.

“This isn’t over, Jackson,” Chrysaor growled. “I will have my revenge—”

His words were cut short by Frank, who had changed form again. An eight-hundred-pound grizzly bear can definitely break up a conversation. He sideswiped Chrysaor and raked the golden mask off his helmet. Chrysaor screamed, instantly covering his face with his arms and tumbling into the water.

They ran to the rail. Chrysaor had disappeared. Percy thought about chasing him, but he didn’t know these waters, and he didn’t want to confront that guy alone again.

“That was brilliant!” Annabeth kissed him, which made him feel a little better.

“It was desperate,” Percy corrected. “And we need to get rid of this pirate trireme.”

“Burn it?” Annabeth asked.

Percy looked at the Diet Coke in his hand. “No. I’ve got another idea.”

It took them longer than Percy wanted. As they worked, he kept glancing at the sea, waiting for Chrysaor and his pirate dolphins to return, but they didn’t.

Leo got back on his feet, thanks to a little nectar. Piper tended to Jason’s wounds, but he wasn’t as badly hurt as he looked. Mostly he was just ashamed that he’d gotten overpowered again, which Percy could relate to.

They returned all their own supplies to the proper places and tidied up from the invasion while Coach Hedge had a field day on the enemy ship, breaking everything he could find with his baseball bat.

When he was done, Percy loaded the enemy’s weapons back on the pirate ship. Their storeroom was full of treasure, but Percy insisted that they touch none of it.

“I can sense about six million dollars’ worth of gold aboard,” Hazel said. “Plus diamonds, rubies—”

“Six m-million?” Frank stammered. “Canadian dollars or American?”

“Leave it,” Percy said. “It’s part of the tribute.”

“Tribute?” Hazel asked.

“Oh.” Piper nodded. “Kansas.”

Jason grinned. He’d been there too when they’d met the wine god. “Crazy. But I like it.”

Finally Percy went aboard the pirate ship and opened the flood valves. He asked Leo to drill a few extra holes in the bottom of the hull with his power tools, and Leo was happy to oblige.

The crew of the Argo II assembled at the rail and cut the grappling lines. Piper brought out her new horn of plenty and, on Percy’s direction, willed it to spew Diet Coke, which came out with the strength of a fire hose, dousing the enemy deck. Percy thought it would take hours, but the ship sank remarkably fast, filling with Diet Coke and seawater.

“Dionysus,” Percy called, holding up Chrysaor’s golden mask. “Or Bacchus—whatever. You made this victory possible, even if you weren’t here. Your enemies trembled at your name…or your Diet Coke, or something. So, yeah, thank you.”

The words were hard to get out, but Percy managed not to gag. “We give this ship to you as tribute. We hope you like it.”

“Six million in gold,” Leo muttered. “He’d better like it.”

“Shh,” Hazel scolded. “Precious metal isn’t all that great. Believe me.”

Percy threw the golden mask aboard the vessel, which was now sinking even faster, brown fizzy liquid spewing out the trireme’s oar slots and bubbling from the cargo hold, turning the sea frothy brown.

Percy summoned a wave, and the enemy ship was swamped. Leo steered the Argo II away as the pirate vessel disappeared underwater.

“Isn’t that polluting?” Piper asked.

“I wouldn’t worry,” Jason told her. “If Bacchus likes it, the ship should vanish.”

Percy didn’t know if that would happen, but he felt like he’d done all he could. He had no faith that Dionysus would hear them or care, much less help them in their battle against the twin giants, but he had to try.

As the Argo II headed east into the fog, Percy decided at least one good thing had come out of his sword fight with Chrysaor. He was feeling humble—even humble enough to pay tribute to the wine dude.

After their bout with the pirates, they decided to fly the rest of the way to Rome. Jason insisted he was well enough to take sentry duty, along with Coach Hedge, who was still so charged with adrenaline that every time the ship hit turbulence, he swung his bat and yelled, “Die!”

They had a couple of hours before daybreak, so Jason suggested Percy try to get a few more hours of sleep.

“It’s fine, man,” Jason said. “Give somebody else a chance to save the ship, huh?”

Percy agreed, though once in his cabin, he had trouble falling asleep.

He stared at the bronze lantern swaying from the ceiling and thought about how easily Chrysaor had beaten him at swordplay. The golden warrior could’ve killed him without breaking a sweat. He’d only kept Percy alive because someone else wanted to pay for the privilege of killing him later.

Percy felt like an arrow had slipped through a chink in his armor—as if he still had the blessing of Achilles, and someone had found his weak spot. The older he got, the longer he survived as a half-blood, the more his friends looked up to him. They depended on him and relied on his powers. Even the Romans had raised him on a shield and made him praetor, and he’d only known them for a couple of weeks.

But Percy didn’t feel powerful. The more heroic stuff he did, the more he realized how limited he was. He felt like a fraud. I’m not as great as you think, he wanted to warn his friends. His failures, like tonight, seemed to prove it. Maybe that’s why he had started to fear suffocation. It wasn’t so much drowning in the earth or the sea, but the feeling that he was sinking into too many expectations, literally getting in over his head.

Wow…when he started having thoughts like that, he knew he’d been spending too much time with Annabeth.

Athena had once told Percy his fatal flaw: he was supposedly too loyal to his friends. He couldn’t see the big picture. He would save a friend even if it meant destroying the world.

At the time, Percy had shrugged this off. How could loyalty be a bad thing? Besides, things worked out okay against the Titans. He’d saved his friends and beaten Kronos.

Now, though, he started to wonder. He would gladly throw himself at any monster, god, or giant to keep his friends from being hurt. But what if he wasn’t up to the task? What if someone else had to do it? That was very hard for him to admit. He even had trouble with simple things like letting Jason take a turn at watch. He didn’t want to rely on someone else to protect him, someone who could get hurt on his account.

Percy’s mom had done that for him. She’d stayed in a bad relationship with a gross mortal guy because she thought it would save Percy from monsters. Grover, his best friend, had protected Percy for almost a year before Percy even realized he was a demigod, and Grover had almost gotten killed by the Minotaur.

Percy wasn’t a kid anymore. He didn’t want anybody he loved taking a risk for him. He had to be strong enough to be the protector himself. But now he was supposed to let Annabeth go off on her own to follow the Mark of Athena, knowing she might die. If it came to a choice—save Annabeth or let the quest succeed—could Percy really choose the quest?

Exhaustion finally overtook him. He fell asleep, and in his nightmare, the rumble of thunder became the laughter of the earth goddess Gaea.

Percy dreamed he was standing on the front porch of the Big House at Camp Half-Blood. The sleeping face of Gaea appeared on the side of Half-Blood Hill—her massive features formed from the shadows on the grassy slopes. Her lips didn’t move, but her voice echoed across the valley.

So this is your home, Gaea murmured. Take a last look, Percy Jackson. You should have returned here. At least then you could have died with your comrades when the Romans invade. Now your blood will be spilled far from home, on the ancient stones, and I will rise.

The ground shook. At the top of Half-Blood Hill, Thalia’s pine tree burst into flames. Disruption rolled across the valley—grass turning to sand, forest crumbling to dust. The river and the canoe lake dried up. The cabins and the Big House burned to ashes. When the tremor stopped, Camp Half-Blood looked like a wasteland after an atomic blast. The only thing left was the porch where Percy stood.

Next to him, the dust swirled and solidified into the figure of a woman. Her eyes were closed, as if she were sleepwalking. Her robes were forest green, dappled with gold and white like sunlight shifting through branches. Her hair was as black as tilled soil. Her face was beautiful, but even with a dreamy smile on her lips she seemed cold and distant. Percy got the feeling she could watch demigods die or cities burn, and that smile wouldn’t waver.

“When I reclaim the earth,” Gaea said, “I will leave this spot barren forever, to remind me of your kind and how utterly powerless they were to stop me. It doesn’t matter when you fall, my sweet little pawn—to Phorcys or Chrysaor or my dear twins. You will fall, and I will be there to devour you. Your only choice now…will you fall alone? Come to me willingly; bring the girl. Perhaps I will spare this place you love. Otherwise…”

Gaea opened her eyes. They swirled in green and black, as deep as the crust of the earth. Gaea saw everything. Her patience was infinite. She was slow to wake, but once she arose, her power was unstoppable.

Percy’s skin tingled. His hands went numb. He looked down and realized he was crumbling to dust, like all the monsters he’d ever defeated.

“Enjoy Tartarus, my little pawn,” Gaea purred.

A metallic CLANG-CLANG-CLANG jolted Percy out of his dream. His eyes shot open. He realized he’d just heard the landing gear being lowered.

There was a knock on his door, and Jason poked his head in. The bruises on his face had faded. His blue eyes glittered with excitement.

“Hey, man,” he said. “We’re descending over Rome. You really should see this.”

The sky was brilliant blue, as if the stormy weather had never happened. The sun rose over the distant hills, so everything below them shone and sparkled like the entire city of Rome had just come out of the car wash.

Percy had seen big cities before. He was from New York, after all. But the sheer vastness of Rome grabbed him by the throat and made it hard to breathe. The city seemed to have no regard for the limits of geography. It spread through hills and valleys, jumped over the Tiber with dozens of bridges, and just kept sprawling to the horizon. Streets and alleys zigzagged with no rhyme or reason through quilts of neighborhoods. Glass office buildings stood next to excavation sites. A cathedral stood next to a line of Roman columns, which stood next to a modern soccer stadium. In some neighborhoods, old stucco villas with red-tiled roofs crowded the cobblestone streets, so that if Percy concentrated just on those areas, he could imagine he was back in ancient times. Everywhere he looked, there were wide piazzas and traffic-clogged streets. Parks cut across the city with a crazy collection of palm trees, pines, junipers, and olive trees, as if Rome couldn’t decide what part of the world it belonged to—or maybe it just believed all the world still belonged to Rome.

It was as if the city knew about Percy’s dream of Gaea. It knew that the earth goddess intended on razing all human civilization, and this city, which had stood for thousands of years, was saying back to her: You wanna dissolve this city, Dirt Face? Give it a shot.

In other words, it was the Coach Hedge of mortal cities—only taller.

“We’re setting down in that park,” Leo announced, pointing to a wide green space dotted with palm trees. “Let’s hope the Mist makes us look like a large pigeon or something.”

Percy wished Jason’s sister Thalia were here. She’d always had a way of bending the Mist to make people see what she wanted. Percy had never been very good at that. He just kept thinking: Don’t look at me, and hoped the Romans below would fail to notice the giant bronze trireme descending on their city in the middle of morning rush hour.

It seemed to work. Percy didn’t notice any cars veering off the road or Romans pointing to the sky and screaming, “Aliens!” The Argo II set down in the grassy field and the oars retracted.

The noise of traffic was all around them, but the park itself was peaceful and deserted. To their left, a green lawn sloped toward a line of woods. An old villa nestled in the shade of some weird-looking pine trees with thin curvy trunks that shot up thirty or forty feet, then sprouted into puffy canopies. They reminded Percy of trees in those Dr. Seuss books his mom used to read him when he was little.

To their right, snaking along the top of a hill, was a long brick wall with notches at the top for archers—maybe a medieval defensive line, maybe Ancient Roman. Percy wasn’t sure.

To the north, about a mile away through the folds of the city, the top of the Colosseum rose above the rooftops, looking just like it did in travel photos. That’s when Percy’s legs started shaking. He was actually here. He’d thought his trip to Alaska had been pretty exotic, but now he was in the heart of the old Roman Empire, enemy territory for a Greek demigod. In a way, this place had shaped his life as much as New York.

Jason pointed to the base of the archers’ wall, where steps led down into some kind of tunnel.

“I think I know where we are,” he said. “That’s the Tomb of the Scipios.”

Percy frowned. “Scipio…Reyna’s pegasus?”

“No,” Annabeth put in. “They were a noble Roman family, and…wow, this place is amazing.”

Jason nodded. “I’ve studied maps of Rome before. I’ve always wanted to come here, but…”

Nobody bothered finishing that sentence. Looking at his friends’ faces, Percy could tell they were just as much in awe as he was. They’d made it. They’d landed in Rome—the Rome.

“Plans?” Hazel asked. “Nico has until sunset—at best. And this entire city is supposedly getting destroyed today.”

Percy shook himself out of his daze. “You’re right. Annabeth…did you zero in on that spot from your bronze map?”

Her gray eyes turned extra thunderstorm dark, which Percy could interpret just fine: Remember what I said, buddy. Keep that dream to yourself.

“Yes,” she said carefully. “It’s on the Tiber River. I think I can find it, but I should—”

“Take me along,” Percy finished. “Yeah, you’re right.”

Annabeth glared daggers at him. “That’s not—”

“Safe,” he supplied. “One demigod walking through Rome alone. I’ll go with you as far as the Tiber. We can use that letter of introduction, hopefully meet the river god Tiberinus. Maybe he can give you some help or advice. Then you can go on alone from there.”

They had a silent staring contest, but Percy didn’t back down. When he and Annabeth started dating, his mother had drummed it into his head: It’s good manners to walk your date to the door. If that was true, it had to be good manners to walk her to the start of her epic solo death quest.

“Fine,” Annabeth muttered. “Hazel, now that we’re in Rome, do you think you can pinpoint Nico’s location?”

Hazel blinked, as if coming out of a trance from watching the Percy/Annabeth Show. “Um…hopefully, if I get close enough. I’ll have to walk around the city. Frank, would you come with me?”

Frank beamed. “Absolutely.”

“And, uh…Leo,” Hazel added. “It might be a good idea if you came along too. The fish-centaurs said we’d need your help with something mechanical.”

“Yeah,” Leo said, “no problem.”

Frank’s smile turned into something more like Chrysaor’s mask.

Percy was no genius when it came to relationships, but even he could feel the tension among those three. Ever since they’d gotten knocked into the Atlantic, they hadn’t acted quite the same. It wasn’t just the two guys competing for Hazel. It was like the three of them were locked together, acting out some kind of murder mystery, but they hadn’t yet discovered which of them was the victim.

Piper drew her knife and set it on the rail. “Jason and I can watch the ship for now. I’ll see what Katoptris can show me. But, Hazel, if you guys get a fix on Nico’s location, don’t go in there by yourselves. Come back and get us. It’ll take all of us to fight the giants.”

She didn’t say the obvious: even all of them together wouldn’t be enough, unless they had a god on their side. Percy decided not to bring that up.

“Good idea,” Percy said. “How about we plan to meet back here at…what?”

“Three this afternoon?” Jason suggested. “That’s probably the latest we could rendezvous and still hope to fight the giants and save Nico. If something happens to change the plan, try to send an Iris-message.”

The others nodded in agreement, but Percy noticed several of them glancing at Annabeth. Another thing no one wanted to say: Annabeth would be on a different schedule. She might be back at three, or much later, or never. But she would be on her own, searching for the Athena Parthenos.

Coach Hedge grunted. “That’ll give me time to eat the coconuts—I mean dig the coconuts out of our hull. Percy, Annabeth…I don’t like you two going off on your own. Just remember: behave. If I hear about any funny business, I will ground you until the Styx freezes over.”

The idea of getting grounded when they were about to risk their lives was so ridiculous, Percy couldn’t help smiling.

“We’ll be back soon,” he promised. He looked around at his friends, trying not to feel like this was the last time they’d ever be together. “Good luck, everyone.”

Leo lowered the gangplank, and Percy and Annabeth were first off the ship.

UNDER DIFFERENT CIRCUMSTANCES, wandering through Rome with Annabeth would have been pretty awesome. They held hands as they navigated the winding streets, dodging cars and crazy Vespa drivers, squeezing through mobs of tourists, and wading through oceans of pigeons. The day warmed up quickly. Once they got away from the car exhaust on the main roads, the air smelled of baking bread and freshly cut flowers.

They aimed for the Colosseum because that was an easy landmark, but getting there proved harder than Percy anticipated. As big and confusing as the city had looked from above, it was even more so on the ground. Several times they got lost on dead-end streets. They found beautiful fountains and huge monuments by accident.

Annabeth commented on the architecture, but Percy kept his eyes open for other things. Once he spotted a glowing purple ghost—a Lar—glaring at them from the window of an apartment building. Another time he saw a white-robed woman—maybe a nymph or a goddess—holding a wicked-looking knife, slipping between ruined columns in a public park. Nothing attacked them, but Percy felt like they were being watched, and the watchers were not friendly.

Finally they reached the Colosseum, where a dozen guys in cheap gladiator costumes were scuffling with the police—plastic swords versus batons. Percy wasn’t sure what that was about, but he and Annabeth decided to keep walking. Sometimes mortals were even stranger than monsters.

They made their way west, stopping every once in a while to ask directions to the river. Percy hadn’t considered that—duh—people in Italy spoke Italian, while he did not. As it turned out, though, that wasn’t much of a problem. The few times someone approached them on the street and asked a question, Percy just looked at them in confusion, and they switched to English.

Next discovery: the Italians used euros, and Percy didn’t have any. He regretted this as soon as he found a tourist shop that sold sodas. By then it was almost noon, getting really hot, and Percy was starting to wish he had a trireme filled with Diet Coke.

Annabeth solved the problem. She dug around in her backpack, brought out Daedalus’s laptop, and typed in a few commands. A plastic card ejected from a slot in the side.

Annabeth waved it triumphantly. “International credit card. For emergencies.”

Percy stared at her in amazement. “How did you—? No. Never mind. I don’t want to know. Just keep being awesome.”

The sodas helped, but they were still hot and tired by the time they arrived at the Tiber River. The shore was edged with a stone embankment. A chaotic assortment of warehouses, apartments, stores, and cafés crowded the riverfront.

The Tiber itself was wide, lazy, and caramel-colored. A few tall cypress trees hung over the banks. The nearest bridge looked fairly new, made from iron girders, but right next to it stood a crumbling line of stone arches that stopped halfway across the river—ruins that might’ve been left over from the days of the Caesars.

“This is it.” Annabeth pointed at the old stone bridge. “I recognize that from the map. But what do we do now?”

Percy was glad she had said we. He didn’t want to leave her yet. In fact, he wasn’t sure he could make himself do it when the time came. Gaea’s words came back to him: Will you fall alone?

He stared at the river, wondering how they could make contact with the god Tiberinus. He didn’t really want to jump in. The Tiber didn’t look much cleaner than the East River back home, where he’d had too many encounters with grouchy river spirits.

He gestured to a nearby café with tables overlooking the water. “It’s about lunchtime. How about we try your credit card again?”

Even though it was noon, the place was empty. They picked a table outside by the river, and a waiter hurried over. He looked a bit surprised to see them—especially when they said they wanted lunch.

“American?” he asked, with a pained smile.

“Yes,” Annabeth said.

“And I’d love a pizza,” Percy said.

The waiter looked like he was trying to swallow a euro coin. “Of course you would, signor. And let me guess: a Coca-Cola? With ice?”

“Awesome,” Percy said. He didn’t understand why the guy was giving him such a sour face. It wasn’t like Percy had asked for a blue Coke.

Annabeth ordered a panini and some fizzy water. After the waiter left, she smiled at Percy. “I think Italians eat a lot later in the day. They don’t put ice in their drinks. And they only do pizza for tourists.”

“Oh.” Percy shrugged. “The best Italian food, and they don’t even eat it?”

“I wouldn’t say that in front of the waiter.”

They held hands across the table. Percy was content just to look at Annabeth in the sunlight. It always made her hair so bright and warm. Her eyes took on the colors of the sky and the cobblestones, alternately brown or blue.

He wondered if he should tell Annabeth his dream about Gaea destroying Camp Half-Blood. He decided against it. She didn’t need anything else to worry about—not with what she was facing.

But it made him wonder…what would have happened if they hadn’t scared off Chrysaor’s pirates? Percy and Annabeth would’ve been put in chains and taken to Gaea’s minions. Their blood would have been spilled on ancient stones. Percy guessed that meant they would’ve been taken to Greece for some big horrible sacrifice. But Annabeth and he had been in plenty of bad situations together. They could’ve figured out an escape plan, saved the day…and Annabeth wouldn’t be facing this solo quest in Rome.

It doesn’t matter when you fall, Gaea had said.

Percy knew it was a horrible wish, but he almost regretted that they hadn’t been captured at sea. At least Annabeth and he would’ve been together.

“You shouldn’t feel ashamed,” Annabeth said. “You’re thinking about Chrysaor, aren’t you? Swords can’t solve every problem. You saved us in the end.”

In spite of himself, Percy smiled. “How do you do that? You always know what I’m thinking.”

“I know you,” she said.

And you like me anyway? Percy wanted to ask, but he held it back.

“Percy,” she said, “you can’t carry the weight of this whole quest. It’s impossible. That’s why there are seven of us. And you’ll have to let me search for the Athena Parthenos on my own.”

“I missed you,” he confessed. “For months. A huge chunk of our lives was taken away. If I lost you again—”

Lunch arrived. The waiter looked much calmer. Having accepted the fact that they were clueless Americans, he had apparently decided to forgive them and treat them politely.

“It is a beautiful view,” he said, nodding toward the river. “Enjoy, please.”

Once he left, they ate in silence. The pizza was a bland, doughy square with not a lot of cheese. Maybe, Percy thought, that’s why Romans didn’t eat it. Poor Romans.

“You’ll have to trust me,” Annabeth said. Percy almost thought she was talking to her sandwich, because she didn’t meet his eyes. “You’ve got to believe I’ll come back.”

He swallowed another bite. “I believe in you. That’s not the problem. But come back from where?”

The sound of a Vespa interrupted them. Percy looked along the riverfront and did a double take. The motor scooter was an old-fashioned model: big and baby blue. The driver was a guy in a silky gray suit. Behind him sat a younger woman with a headscarf, her hands around the man’s waist. They weaved between café tables and puttered to a stop next to Percy and Annabeth.

“Why, hello,” the man said. His voice was deep, almost croaky, like a movie actor’s. His hair was short and greased back from his craggy face. He was handsome in a 1950s dad-on-television way. Even his clothes seemed old-fashioned. When he stepped off his bike, the waistline of his slacks was way higher than normal, but somehow he still managed to look manly and stylish and not like a total goober. Percy had trouble guessing his age—maybe thirty-something, though the man’s fashion and manner seemed grandfatherish.

The woman slid off the bike. “We’ve had the most lovely morning,” she said breathlessly.

She looked about twenty-one, also dressed in an old-fashioned style. Her ankle-length marigold skirt and white blouse were pinched together with a large leather belt, giving her the narrowest waist Percy had ever seen. When she removed her scarf, her short wavy black hair bounced into perfect shape. She had dark playful eyes and a brilliant smile. Percy had seen naiads that looked less pixieish than this lady.

Annabeth’s sandwich fell out of her hands. “Oh, gods. How—how… ?”

She seemed so stunned that Percy figured he ought to know these two.

“You guys do look familiar,” he decided. He thought he might have seen their faces on television. It seemed like they were from an old show, but that couldn’t be right. They hadn’t aged at all. Nevertheless, he pointed at the guy and took a guess. “Are you that guy on Mad Men?”

“Percy!” Annabeth looked horrified.

“What?” he protested. “I don’t watch a lot of TV.”

“That’s Gregory Peck!” Annabeth’s eyes were wide, and her mouth kept falling open. “And…oh gods! Audrey Hepburn! I know this movie. Roman Holiday. But that was from the 1950s. How—?”

“Oh, my dear!” The woman twirled like an air spirit and sat down at their table. “I’m afraid you’ve mistaken me for someone else! My name is Rhea Silvia. I was the mother to Romulus and Remus, thousands of years ago. But you’re so kind to think I look as young as the 1950s. And this is my husband…”

“Tiberinus,” said Gregory Peck, thrusting out his hand to Percy in a manly way. “God of the River Tiber.”

Percy shook his hand. The guy smelled of aftershave. Of course, if Percy were the Tiber River, he’d probably want to mask the smell with cologne too.

“Uh, hi,” Percy said. “Do you two always look like American movie stars?”

“Do we?” Tiberinus frowned and studied his clothes. “I’m not sure, actually. The migration of Western civilization goes both ways, you know. Rome affected the world, but the world also affects Rome. There does seem to be a lot of American influence lately. I’ve rather lost track over the centuries.”

“Okay,” Percy said. “But…you’re here to help?”

“My naiads told me you two were here.” Tiberinus cast his dark eyes toward Annabeth. “You have the map, my dear? And your letter of introduction?”

“Uh…” Annabeth handed him the letter and the disk of bronze. She was staring at the river god so intently Percy started to feel jealous.

“S-so…” she stammered, “you’ve helped other children of Athena with this quest?”

“Oh, my dear!” The pretty lady, Rhea Silvia, put her hand on Annabeth’s shoulder. “Tiberinus is ever so helpful. He saved my children Romulus and Remus, you know, and brought them to the wolf goddess Lupa. Later, when that old king Numen tried to kill me, Tiberinus took pity on me and made me his wife. I’ve been ruling the river kingdom at his side ever since. He’s just dreamy!”

“Thank you, my dear,” Tiberinus said with a wry smile. “And, yes, Annabeth Chase, I’ve helped many of your siblings…to at least begin their journey safely. A shame all of them died painfully later on. Well, your documents seem in order. We should get going. The Mark of Athena awaits!”

Percy gripped Annabeth’s hand—probably a little too tight. “Tiberinus, let me go with her. Just a little farther.”

Rhea Silvia laughed sweetly. “But you can’t, silly boy. You must return to your ship and gather your other friends. Confront the giants! The way will appear in your friend Piper’s knife. Annabeth has a different path. She must walk alone.”

“Indeed,” Tiberinus said. “Annabeth must face the guardian of the shrine by herself. It is the only way. And Percy Jackson, you have less time than you realized to rescue your friend in the jar. You must hurry.”

Percy’s pizza felt like a cement lump in his stomach. “But—”

“It’s all right, Percy.” Annabeth squeezed his hand. “I need to do this.”

He started to protest. Her expression stopped him. She was terrified but doing her best to hide it—for his sake. If he tried to argue, he would only make things harder for her. Or worse, he might convince her to stay. Then she would have to live with the knowledge that she’d backed down from her biggest challenge…assuming that they survived at all, with Rome about to get leveled and Gaea about to rise and destroy the world. The Athena statue held the key to defeating the giants. Percy didn’t know why or how, but Annabeth was the only one who could find it.

“You’re right,” he said, forcing out the words. “Be safe.”

Rhea Silvia giggled like it was a ridiculous comment. “Safe? Not at all! But necessary. Come, Annabeth, my dear. We will show you where your path starts. After that, you’re on your own.”

Annabeth kissed Percy. She hesitated, like she was wondering what else to say. Then she shouldered her backpack and climbed on the back of the scooter.

Percy hated it. He would’ve preferred to fight any monster in the world. He would’ve preferred a rematch with Chrysaor. But he forced himself to stay in his chair and watch as Annabeth motored off through the streets of Rome with Gregory Peck and Audrey Hepburn.

ANNABETH FIGURED IT COULD’VE BEEN WORSE. If she had to go on a horrifying solo quest, at least she’d gotten to have lunch with Percy on the banks of the Tiber first. Now she got to take a scooter ride with Gregory Peck.

She only knew about that old movie because of her dad. Over the past few years, since the two of them had made up, they’d spent more time together, and she had learned that her dad had a sappy side. Sure, he liked military history, weapons, and biplanes, but he also loved old films, especially romantic comedies from the 1940s and ’50s. Roman Holiday was one of his favorites. He’d made Annabeth watch it.

She thought the plot was silly—a princess escapes her minders and falls in love with an American journalist in Rome—but she suspected her dad liked it because it reminded him of his own romance with the goddess Athena: another impossible pairing that couldn’t end happily. Her dad was nothing like Gregory Peck. Athena certainly wasn’t anything like Audrey Hepburn. But Annabeth knew that people saw what they wanted to see. They didn’t need the Mist to warp their perceptions.

As the baby-blue scooter zipped through the streets of Rome, the goddess Rhea Silvia gave Annabeth a running commentary on how the city had changed over the centuries.

“The Sublician Bridge was over there,” she said, pointing to a bend in the Tiber. “You know, where Horatius and his two friends defended the city from an invading army? Now, there was a brave Roman!”

“And look, dear,” Tiberinus added, “that’s the place where Romulus and Remus washed ashore.”

He seemed to be talking about a spot on the riverside where some ducks were making a nest out of torn-up plastic bags and candy wrappers.

“Ah, yes,” Rhea Silvia sighed happily. “You were so kind to flood yourself and wash my babies ashore for the wolves to find.”

“It was nothing,” Tiberinus said.

Annabeth felt light-headed. The river god was talking about something that had happened thousands of years ago, when this area was nothing but marshes and maybe some shacks. Tiberinus saved two babies, one of whom went on to found the world’s greatest empire. It was nothing.

Rhea Silvia pointed out a large modern apartment building. “That used to be a temple to Venus. Then it was a church. Then a palace. Then an apartment building. It burned down three times. Now it’s an apartment building again. And that spot right there—”

“Please,” Annabeth said. “You’re making me dizzy.”

Rhea Silvia laughed. “I’m sorry, dear. Layers upon layers of history here, but it’s nothing compared to Greece. Athens was old when Rome was a collection of mud huts. You’ll see, if you survive.”

“Not helping,” Annabeth muttered.

“Here we are,” Tiberinus announced. He pulled over in front of a large marble building, the facade covered in city grime but still beautiful. Ornate carvings of Roman gods decorated the roofline. The massive entrance was barred with iron gates, heavily padlocked.

“I’m going in there?” Annabeth wished she’d brought Leo, or at least borrowed some wire cutters from his tool belt.

Rhea Silvia covered her mouth and giggled. “No, my dear. Not in it. Under it.”

Tiberinus pointed to a set of stone steps on the side of the building—the sort that would have led to a basement apartment if this place were in Manhattan.

“Rome is chaotic aboveground,” Tiberinus said, “but that’s nothing compared to below ground. You must descend into the buried city, Annabeth Chase. Find the altar of the foreign god. The failures of your predecessors will guide you. After that…I do not know.”

Annabeth’s backpack felt heavy on her shoulders. She’d been studying the bronze map for days now, scouring Daedalus’s laptop for information. Unfortunately, the few things she had learned made this quest seem even more impossible. “My siblings…none of them made it all the way to the shrine, did they.”

Tiberinus shook his head. “But you know what prize awaits, if you can liberate it.”

“Yes,” Annabeth said.

“It could bring peace to the children of Greece and Rome,” Rhea Silvia said. “It could change the course of the coming war.”

“If I live,” Annabeth said.

Tiberinus nodded sadly. “Because you also understand the guardian you must face?”

Annabeth remembered the spiders at Fort Sumter, and the dream Percy had described—the hissing voice in the dark. “Yes.”

Rhea Silvia looked at her husband. “She is brave. Perhaps she is stronger than the others.”

“I hope so,” said the river god. “Good-bye, Annabeth Chase. And good luck.”

Rhea Silvia beamed. “We have such a lovely afternoon planned! Off to shop!”

Gregory Peck and Audrey Hepburn sped off on their baby-blue motorbike. Then Annabeth turned and descended the steps alone.

She’d been underground plenty of times.

But halfway down the steps, she realized just how long it had been since she’d adventured by herself. She froze.

Gods…she hadn’t done something like this since she was a kid. After running away from home, she’d spent a few weeks surviving on her own, living in alleyways and hiding from monsters until Thalia and Luke took her under their wings. Then, once she’d arrived at Camp Half-Blood, she’d lived there until she was twelve. After that, all her quests had been with Percy or her other friends.

The last time she had felt this scared and alone, she’d been seven years old. She remembered the day Thalia, Luke, and she had wandered into a Cyclopes’ lair in Brooklyn. Thalia and Luke had gotten captured, and Annabeth had had to cut them free. She still remembered shivering in a dark corner of that dilapidated mansion, listening to the Cyclopes mimicking her friends’ voices, trying to trick her into coming out into the open.

What if this is a trick, too? she wondered. What if those other children of Athena died because Tiberinus and Rhea Silvia led them into a trap? Would Gregory Peck and Audrey Hepburn do something like that?

She forced herself to keep going. She had no choice. If the Athena Parthenos was really down here, it could decide the fate of the war. More importantly, it could help her mom. Athena needed her.

At the bottom of the steps she reached an old wooden door with an iron pull ring. Above the ring was a metal plate with a keyhole. Annabeth started considering ways to pick the lock, but as soon as she touched the pull ring, a fiery shape burned in the middle of the door: the silhouette of Athena’s owl. Smoke plumed from the keyhole. The door swung inward.

Annabeth looked up one last time. At the top of the stairwell, the sky was a square of brilliant blue. Mortals would be enjoying the warm afternoon. Couples would be holding hands at the cafés. Tourists would be bustling through the shops and museums. Regular Romans would be going about their daily business, probably not considering the thousands of years of history under their feet, and definitely unaware of the spirits, gods, and monsters that still dwelt here, or the fact that their city might be destroyed today unless a certain group of demigods succeeded in stopping the giants.

Annabeth stepped through the doorway.

She found herself in a basement that was an architectural cyborg. Ancient brick walls were crisscrossed with modern electrical cables and plumbing. The ceiling was held up with a combination of steel scaffolding and old granite Roman columns.

The front half of the basement was stacked with crates. Out of curiosity, Annabeth opened a few. Some were packed with multicolored spools of string—like for kites or arts and crafts projects. Other crates were full of cheap plastic gladiator swords. Maybe at one point this had been a storage area for a tourist shop.

In the back of the basement, the floor had been excavated, revealing another set of steps—these of white stone—leading still deeper underground.

Annabeth crept to the edge. Even with the glow cast by her dagger, it was too dark to see below. She rested her hand on the wall and found a light switch.

She flipped it. Glaring white fluorescent bulbs illuminated the stairs. Below, she saw a mosaic floor decorated with deer and fauns—maybe a room from an Ancient Roman villa, just stashed away under this modern basement along with the crates of string and plastic swords.

She climbed down. The room was about twenty feet square. The walls had once been brightly painted, but most of the frescoes had peeled or faded. The only exit was a hole dug in one corner of the floor where the mosaic had been pulled up. Annabeth crouched next to the opening. It dropped straight down into a larger cavern, but Annabeth couldn’t see the bottom.

She heard running water maybe thirty or forty feet below. The air didn’t smell like a sewer—just old and musty, and slightly sweet, like moldering flowers. Perhaps it was an old water line from the aqueducts. There was no way down.

“I’m not jumping,” she muttered to herself.

As if in reply, something glowed in the darkness. The Mark of Athena blazed to life at the bottom of the cavern, revealing glistening brickwork along a subterranean canal forty feet below. The fiery owl seemed to be taunting her: Well, this is the way, kid. So you’d better figure something out.

Annabeth considered her options. Too dangerous to jump. No ladders or ropes. She thought about borrowing some metal scaffolding from above to use as a fire pole, but it was all bolted in place. Besides, she didn’t want to cause the building to collapse on top of her.

Frustration crawled through her like an army of termites. She had spent her life watching other demigods gain amazing powers. Percy could control water. If he were here, he could raise the water level and simply float down. Hazel, from what she had said, could find her way underground with flawless accuracy and even create or change the course of tunnels. She could easily make a new path. Leo would pull just the right tools from his belt and build something to do the job. Frank could turn into a bird. Jason could simply control the wind and float down. Even Piper with her charmspeak…she could have convinced Tiberinus and Rhea Silvia to be a little more helpful.

What did Annabeth have? A bronze dagger that did nothing special, and a cursed silver coin. She had her backpack with Daedalus’s laptop, a water bottle, a few pieces of ambrosia for emergencies, and a box of matches—probably useless, but her dad had drilled into her head that she should always have a way to make fire.

She had no amazing powers. Even her one true magic item, her New York Yankees cap of invisibility, had stopped working, and was still back in her cabin on the Argo II.

You’ve got your intelligence, a voice said. Annabeth wondered if Athena was speaking to her, but that was probably just wishful thinking.

Intelligence…like Athena’s favorite hero, Odysseus. He’d won the Trojan War with cleverness, not strength. He had overcome all sorts of monsters and hardships with his quick wits. That’s what Athena valued.

Wisdom’s daughter walks alone.

That didn’t mean just without other people, Annabeth realized. It meant without any special powers.

Okay…so how to get down there safely and make sure she had a way to get out again if necessary?

She climbed back to the basement and stared at the open crates. Kite string and plastic swords. The idea that came to her was so ridiculous, she almost had to laugh; but it was better than nothing.

She set to work. Her hands seemed to know exactly what to do. Sometimes that happened, like when she was helping Leo with the ship’s machinery or drawing architectural plans on the computer. She’d never made anything out of kite string and plastic swords, but it seemed easy, natural. Within minutes she’d used a dozen balls of string and a crateful of swords to create a makeshift rope ladder—a braided line, woven for strength yet not too thick, with swords tied at two-foot intervals to serve as hand-and footholds.

As a test, she tied one end around a support column and leaned on the rope with all her weight. The plastic swords bent under her, but they provided some extra bulk to the knots in the cord, so at least she could keep a better grip.

The ladder wouldn’t win any design awards, but it might get her to the bottom of the cavern safely. First, she stuffed her backpack with the leftover spools of string. She wasn’t sure why, but they were one more resource, and not too heavy.