2070-71. Nearly six decades after Step Day, a new society continues to evolve in the Long Earth. Now, a message has been received: Join us. The Next-- the hyper-intelligent post-humans-- realize that the missive contains instructions for kick-starting the development of an immense artificial intelligence known as The Machine. But to build a computer the size of a continent, they must obtain help from the still industrious worlds of mankind. Meanwhile, Joshua ValientA© is saved from death when a troll band discovers him. Living among the trolls as he recovers, Joshua develops a deeper understanding of this collective-intelligence species and its society.