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 involved with this perilous work when, out of the blue, Sally is certainly contacted by her long-vanished dad and inventor of the original Stepper gadget, Willis Linsay. He tells her he is planning a amazing voyage over the Long Mars and wants her to accompany him. But Sally soon learns that Willis offers ulterior motives …

On the other hand U. S. Navy Commander Maggie Kauffman has embarked on an incredible journey of her own, leading an expedition to the external limits of the far Long Earth.

For Joshua, the problems he faces is much closer to home. He becomes embroiled in the plight of another: the super-bright post-humans who are starting to emerge off their ‘lengthy childhood’ locally called Happy Landings, located deep in the Long Globe. Ignorance and fear are leading to ‘normal’ human culture to carefully turn against another – and a dramatic showdown seems inevitable .