2070-71. Nearly six decades after Step Day and in the Long Earth, the new Next post-human society continues to evolve. For Joshua Valienté, now in his late sixties, it is time to take one last solo journey into the High Meggers: an adventure that turns into a disaster. Alone and facing death, his only hope of salvation lies with a group of trolls. But as Joshua confronts his mortality, the Long Earth receives a signal from the stars. A signal that is picked up by radio astronomers but also in more abstract ways – by the trolls and by the Great Traversers. Its message is simple but ts implications are enormous: