It is the middle of the 21st century.
After the cataclysmic upheavals of Step Day and the Yellowstone eruption, humanity is spreading further into the Long Earth. Society, on a battered Datum Earth and beyond, continues to evolve.
And new challenges emerge.
Now an elderly and cantankerous AI, Lobsang is living with Agnes in an exotic, far-distant world. He’s determined to lead a normal life in New Springfield – they even adopt a child. But there are rumours, strange sightings in the sky. On this world, something isn’t right . . .
Millions of steps away – while learning about a hidden family history and the father he never knew – Joshua receives an urgent summons from New Springfield.
Lobsang has come to understand that what has blighted his Earth is a threat to all the worlds of the Long Earth. To counter this threat will require the combined efforts of humankind, machine and the super-intelligent Next. And some must make the ultimate sacrifice . . .