The frontier of the Solar System! A vast and gloomy darkness, a region of eternal night remote by six billion trackless miles from the far, bright star of the sun. A cold and awful immensity of space beyond which stretches only the shoreless sea of the interstellar void.
Yet even out into these far, dark spaces reached the invisible grip of the sun, to hold the outermost of its planetary children. Out here in eternal silence and darkness, far from the flaming orb that gave it birth, solemnly moved the dim world of Erebus on its slow, stupendous patrol.
A ship was moving out through the colossal dark toward the last planet. It was moving at tremendous speed under inertia, yet it seemed merely to be crawling through the vast emptiness as it held its course toward the dim, slowly enlarging sphere of Erebus.
John Thorn peered fixedly from the window of the control-room at the mysterious world ahead. It was like a little ghost-world, shining in the dark vault with a feeble blue light.
"It must have an extraordinarily high albedo to reflect so much sunlight at this distance,” Thorn muttered.
"Yes, it's cursed queer,” Sual Av agreed, frowning intently.
Beside the Planeteers, who had discarded their Saturnian disguises, old Stilicho Keene peered forward, a haunting apprehension in his faded eyes. The space dog crouched at his feet.
Gunner Welk was at the eyepiece of the ‘scope, staring toward dim Erebus. The towering Mercurian turned to Thorn.
"Cheerly's ship isn't in sight, John,” he rumbled. “He must already have landed on Erebus."
Thorn's brown face contorted in agonized emotion.
"We should have overtaken him!” he cried, his voice raw and self-accusing. “If we'd put on a little more speed—"
"But boy, the Venture's been at top speed in all the long days since we left Saturn!” Stilicho quivered. “It's been like a nightmare voyage, with the power-chambers throbbing to the limit, and my crew getting more scared each day, and us sailin’ on toward God knows what on that world ahead!"
It had, indeed, seemed like a strange dream to all of them as their craft had, for days, crept out into the trackless, forbidding immensities. Stilicho's pirate crew had whispered fearfully, only the hope of rescuing their idolized girl leader keeping them from mutinying. An alien chill gripped all except John Thorn.
Thorn had become more and more feverishly anxious each day, as he thought of Jenk Cheerly speeding on with Lana to seize the precious radite — the radite whose taking would signal Lana's death and the launching of Trask's attack on the Alliance!
"Shall I try the spectro-telescope?” Gunner was asking. “We're near enough to Erebus for it to detect the radite."
Thorn nodded quickly. “The radite should show up clearly. I'll check our aura again for Cheerly's ship."
Thorn snapped on the aura. But something was wrong. The aurachart did not come on. The device was dead.
"What the devil?” Sual Av muttered astonishedly. “Something must be jamming the ether to kill our aura like that."
"All our other instruments are dead, too!” burst out Stilicho, looking up worriedly from the panel. “The gravitometers and space-sextants and even the audio!"
"Is it some trick of Cheerly's?” Sual Av cried.
"It couldn't be — he wouldn't have power enough to jam the ether like this,” Thorn declared.
Gunner Welk swung around from his instrument, his massive face puzzled.
"John, there's something wrong with this spectro-telescope, too,” he said. “I adjusted its limits to the field of radioactive elements, but all of Erebus still shows up in it."
Old Stilicho looked anxiously from the faintly shining blue ghost-world ahead, to the puzzled Planeteers.
"We'll soon be close to Erebus,” the old pirate said. “What are we going to do? Land and hunt for Lana on foot?"
There was lurking terror in his faded eyes as he made the proposition, yet he kept his shrill voice steady.
"We dare not just sail in and land,” Thorn muttered. ‘It might mean the end of us, right there."
His face worked. “Yet we daren't lose time either! If Lana had only been able to tell us the secret."
"John, remember what Cheerly told Trask in. our cell on Saturn, after he'd got the secret from Lana!” Sual Av said eagerly. “That he'd learned from Lana that there was only one spot on Erebus where men could land without meeting a ghastly fate!"
"One spot, but where is it?” Gunner demanded. “There's no use of our hunting for that spot, for we wouldn't know it if we saw it."
"Yes, we would know it!” Thorn cried suddenly. “Cheerly's ship would have landed in that one safe spot. If we can find where Cheerly has landed here, we can land safely beside him!"
He swung around to Stilicho Keene. “We'll reduce speed and circle around Erebus looking for Cheerly's ship. Don't go lower than a hundred miles above the surface."
Unutterable tension gripped the Planeteers and the old pirate as the Venture swept in closer toward the mysterious planet from which only one man in all history had returned. Erebus slowly expanded ahead, a small world hardly larger than Mercury. At last the ship dropped to within a hundred miles of its surface.
It was a strangely luminous planetscape they looked down upon, a world shimmering everywhere with the dusky blue radiance they had noticed from afar. They had thought that faint luminescence a trick of reflected sunlight, but they saw now that it was somehow inherent in this world. Through that dusky blue haze they looked down upon a weirdly forbidding landscape.
Low, jagged, barren mountains rose like fangs bared at the dark, star-studded sky. Beyond their rocky slopes stretched dim deserts, wide blank wastes upon which moved little whirls of dust. And all this dreary landscape of eternal twilight was wrapped in the uncanny faint blue radiance.
"It's queer, the way it all shines,” muttered Sual Av. “But I can't see anything dangerous down there."
"There's something dangerous there — terribly so,” Thorn said tautly. “If there weren't, this world wouldn't have swallowed up so many hundreds of explorers in the last nine centuries!"
"There's air of some kind down there, anyway,” old Stilicho quavered. “See them there whirling dust-devils?"
"But there can't be an atmosphere here!” Gunner declared. “That would mean that Erebus is comparatively warm, and what would keep it warm at this distance from the sun?"
"Everything about this world is wrong, somehow,” Thorn muttered. “The way it shines, its warmth and atmosphere, the way our instruments went dead when we neared it."
The Venture was now moving on an even keel a hundred miles above the surface of the ghostly blue planet. Stilicho handled the controls as they moved at reduced speed around the equator of the mystery world. Gunner Welk swept the terrain beneath with the ‘scope as they sped along.
The cruel, barren mountains swept back and disappeared in the glowing blue haze behind them. They moved on above the endless wastes of faintly shining desert.
"Thought I saw something shiny moving down there,” Gunner exclaimed in a moment. “My eyes must be playing me trick!"
"Cheerly's ship is what we want to find,” Thorn rapped. “It's somewhere here. He hasn't had time to lift the radite and leave, considering how fast we followed him."
Within a few hours, they had completely circumnavigated the equator of the little mystery world. They had seen nothing but the deathly deserts and mountains, wrapped in. the unchanging, shimmering blue haze.
"Run north and circle the planet again midway between the equator and the pole,” Thorn ordered Stilicho.
"It's kind of like looking for a needle in a haystack, hunting one ship on a whole world,” Stilicho muttered.
"This world isn't big. We'll sweep every mile of it if necessary,” John Thorn declared.
Soon they were again circling Erebus, midway between the equator and the northern pole. Before they had gone far, Gunner pointed to a black speck on the northern desert horizon.
"Something odd about that black mountain yonder!” he reported from the ‘scope eyepiece. “It has none of the shining haze over it — the only place I've seen here that hasn't."
"Steer toward it, but keep high,” John Thorn told the old pirate.
"We'll take a look."
The black speck on the horizon expanded rapidly as the ship rocketed north. It grew into a big black mountain that loomed in solitary majesty out of a wide expanse of the haze-wrapped desert. brooding beneath the star-flecked dark sky.
It was a mountain almost perfectly dome-shaped, the regularity of its outline startling. It was two miles across at the base and a mile in height. It stood out bold and black because none of the shining blue haze hovered over it.
"Queer, the symmetrical shape of that mountain,” Sual Av muttered. “Is it possible that it is—"
"'There's a ship parked on that mountain!” Gunner Welk yelled suddenly in high excitement,
Thorn leaped to the ‘scope eyepiece. The huge, frowning black mass of the domed mountain jumped into close view. Upon the curved, rough eastern side of the great mass, near the top, rested a long, torpedo-like metal shape.
"It's Cheerly's cruiser!” Thorn exclaimed. “If they landed on that black mountain, it must be the one spot on Erebus where it's safe to land. We're going to land there and seize his ship!"
He swung, his pulses hammering. “Veer off, Stilicho, and run back toward the mountain from the west at a mile altitude. Cheerly can't have seen us yet. We'll land on the west side of the mountain and take him by surprise!"
The old pirate swung the Venture in a wide detour, and soon they were rocketing low toward the mountain from the west, hidden by the domed mass from the ship parked on the other side. Expertly, the old Martian brought the ship down to a landing on the rough, curved western side of the great mass.
As the blasting roar of the rockets died, Sual Av turned from the instrument he had been manipulating.
"The atmosphere checks as air, but loaded with elements I can't identify without analysis,” he reported.
"We'll play safe and wear our spacesuits,” Thorn declared. “Come on!"
They hastened down into the midcompartment of the ship. Stilicho's motley pirate crew were waiting there, all of them looking a little scared by the fact that they had actually landed upon the surface of Erebus.
"We're going over the top of this mountain to find and capture Cheerly's ship, Thom rapped to them. “On suits, everybody! And bring all the dampers we have. There's to be no using of atom-guns unless absolutely necessary, for we don't want to hurt Lana."
Five minutes later, the big door port of the Venture ground open. Out through the air-lock moved the company of forty men, all in suits and helmets, with John Thorn in the lead.
Thorn noted that they stepped out onto a rough jagged surface of black metal. The whole mountain, it seemed, was of black metal, pocked here and there with deposits of glistening ores. The top of the dome-shaped mass loomed starkly against the dusky, starry sky.
Thorn could not repress a tautening of his nerves. This was Erebus, the forbidden world that had claimed so many explorers’ lives since nine centuries ago. From the curving side of the mountain on which the Venture lay, he could look out westward across the barren deserts, wrapped in mysterious, shimmering blue radiance.
The little party was armed with several of the cylindrical dampers that could put atom-guns out of commission, and with atom-pistols belted outside their space-suits. They started up the side of the metal mountain, trudging against a gravitation that was surprisingly strong for so small a world. The Planeteers and old Stilicho led, and beside them ran the space dog, Ool, his green eyes blazing as though he sensed they were on the same world as Lana Cain.
They reached the top of the domed mountain, and Thorn crouched down with his comrades to reconnoiter. Cheerly’ s ship, a long, many-gunned Saturnian naval cruiser with the name Gargol on its bows, lay only a few hundred yards down the curved rough metal slope. They could see a few men in space-suits outside the ship, digging glistening ores from the deposits that packed the metal mountain,
Sual Av's voice reached Thorn by conduction, as the Planeteers crouched with the old pirate and the space dog.
"They're digging fuel-ores for the return trip,” the Venusian muttered. “They can't have sighted our ship."
Thorn nodded his glassite helmet tensely. “Here we go,’ he said, rising to his feet and signaling the pirates behind them. “Whatever you do, be careful you don't injure Lana!"
The space-suited attackers swept down the rough curve of the mountain in a silent run toward the Saturnian ship. They were half-way to it before one of the diggers there glimpsed them,
Instantly, the man fired his atom-pistol at them. The little shell struck a man behind Thorn, a pirate who fell as the blinding flare of energy enveloped him. Thorn swung the damper he carried toward the Saturnian who had fired, and killed his weapon. “Quick, men!” Thorn yelled, then remembered that their audios were off, and signaled with his arm.
The little pirate band swept fiercely down the metal slope. Out of the ship, Saturnians in space-suits were pouring and leveling atom-pistols. The dampers carried by Thorn and several of his men deadened many of the weapons, but atom-shells from others flared blindingly among the pirates and felled a half dozen men,
Then Thorn and his followers reached the Saturnians. It became a fierce fight at close quarters, shells of atom-pistols flaring and men falling, under the solemn stars of the darkly. The space dog leaped and tore horribly with his great teeth and talons among the enemy. Thorn swung his heavy cylindrical damper as a great club as he and Gunner and Sual Av fought forward.
The Saturnians, appalled by the fierceness of the pirate attack, scrambled back through the air-lock of the ship.
"After them!” Thorn cried, waving his arm in a fierce forward gesture. “Don't let them get away with the ship."
Gunner flung the damper he carried, and it jammed the air-lock door. Then Thorn's men were pushing into the ship.
In ten minutes, the fight inside the ship was ended, Taken by surprise, unprepared for an attack, the Saturnian crew had not been able to withstand the rush of Thorn's followers.
A dozen of the Saturnians lying dead, the survivors stood with hands raised in surrender. As soon as the air-lock door was closed and the oxygenerators functioning, Thorn ripped off his helmet and ordered the massed prisoners to take off their helmets also.
As each sullen green Saturnian face emerged to view, Thorn's pulse pounded. But when all the prisoners were unhelmeted, he felt a shock of bitter disappointment. Neither Jenk Cheerly nor Lana were in the ship!
"Where's Cheerly and the girl?” he demanded fiercely of the crestfallen Saturnian cruiser captain.
"Cheerly left here yesterday, taking two men and the pirate girl,” answered the captain sullenly. “They went toward those mountains westward."
"Cheerly had located the radite there?” Sual Av cried eagerly. The Saturnian nodded sulkily.
"Yes, after we landed our ship here, Cheerly worked with our spectroscopes until he ascertained that the deposit of radite lay somewhere in, those mountains. He took the girl with him because he, believed she knows exactly where it is, though she said she didn't."
"Then all we have to do is to wait till Cheerly comes back here with the radite, and grab him!” Gunner exclaimed.
"No, we can't do that!” Thorn cried. “Cheerly would bring back the radite, but he wouldn't bring back Lana! We've got to go after him!"
"In our ship?” old Stilicho asked eagerly.
Thorn shook his head. “We daren't. This is the one safe place on Erebus where a ship can land, remember. We'll have to follow on foot, in our space-suits."
He saw a quick gleam of satisfaction in the sullen eyes of the Saturnian captain. And Thorn's face tightened.
"You will come along with us,” he told the green-faced captain suspiciously.
The Saturnian went livid. “I won't go!” he gasped, all secret satisfaction gone at once, “I won't!"
Thorn seized him by the throat. “Why not?” he harked “What are you afraid of? What is it that makes you glad at the idea of us going on foot to those mountains?"
The Saturnian was silent, helpless rage and fear contending in his face.
"Tell, or I'll make you walk out there by yourself!” Thorn menaced. The threat crumpled the captain's spirit.
"I'll tell!” he gasped. “It means a hideous doom if you venture off this mountain without protection. For all the matter of those deserts and mountains out there, all the matter of Erebus except this single metal mountain, is radioactive matter.
"Erebus is a radioactive world. That's the secret the pirate girl knew, that no one else guessed. A ship that landed anywhere except on this mountain would instantly itself become radioactive by induced radioactivity from the soil on which it landed. The same fate would befall an unprotected man who stepped off this mountain. This metal mountain is the only non-radioactive matter on the whole planet!"