2040-2045: In the years after the cataclysmic Yellowstone eruption there is massive economic dislocation as populations flee Datum Earth to myriad Long Earth worlds. Sally, Joshua, and Lobsang are all involved in this perilous work when, out of the blue, Sally is contacted by her long-vanished father and inventor of the original Stepper device, Willis Linsay. He tells her he is planning a fantastic voyage across the Long Mars and wants her to accompany him. But Sally soon learns that Willis has ulterior motives ...
Meanwhile U. S. Navy Commander Maggie Kauffman has embarked on an incredible journey of her own, leading an expedition to the outer limits of the far Long Earth.
For Joshua, the crisis he faces is much closer to home. He becomes embroiled in the plight of the Next: the super-bright post-humans who are beginning to emerge from their 'long childhood' in the community called Happy Landings, located deep in the Long Earth. Ignorance and fear are causing 'normal' human society to turn against the Next - and a dramatic showdown seems inevitable . . .
The third Long Earth installment (after The Long War) sees humanity spreading out across infinite parallel worlds, with several key figures trailblazing in different ways. Commander Maggie Kauffman leads an expedition to catalog hundreds of millions of Earths, many of which prove far stranger and less hospitable than imagined. Sally Linsay is recruited by her father to explore the alternates of the newly-discovered Long Mars in search of intelligent life. Joshua Valiente encounters the emerging Next, a new breed of superintelligent humans raised in Long Earth, whose development is bringing them at odds with baseline humanity. These first two threads offer up fascinating and inventive takes on planetary development, though they fly by at dizzying speeds. The third feels too much like a conventional "us vs. them" plot. Nonetheless, Baxter and Pratchett remain in fine form, their collaboration producing another thoughtful page-turner.