A generation after the events of The Long Earth, mankind has spread across the new worlds opened up by Stepping. Where Joshua and Lobsang once pioneered, now fleets of airships link the stepwise Americas with trade and culture. Mankind is shaping the Long Earth - but in turn the Long Earth is shaping mankind ... A new `America', called Valhalla, is emerging more than a million steps from Datum Earth, with core American values restated in the plentiful environment of the Long Earth - and Valhalla is growing restless under the control of the Datum government... Meanwhile the Long Earth is suffused by the song of the trolls, graceful hive-mind humanoids. But the trolls are beginning to react to humanity's thoughtless exploitation ... Joshua, now a married man, is summoned by Lobsang to deal with a gathering multiple crisis that threatens to plunge the Long Earth into a war unlike any mankind has waged before.

Meet Jill, the unhinged owner of a small town beauty salon, and enter her dysfunctional world. Pretending that her hospitalised husband is dying, Jill is on a mission to find a man. She joins the "Lassoo the Moon" Dating Agency, but when her dates don't come up to scratch, she sets her sights on her neighbour Don, a doctor, and develops a very unhealthy obsession about him. Moving in to 'nurse' his terminally ill wife, she is determined to seduce him and bring their marriage to a grinding halt... by ANY means necessary. So will she get her man in the end?

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 . . .

2045-2059. After the cataclysmic upheavals of Step Day and the Yellowstone eruption humanity is spreading further into the Long Earth, and society, on a battered Datum Earth and beyond, continues to evolve. Now an elderly and cantankerous AI, Lobsang lives in disguise with Agnes in an exotic, far-distant world. He's convinced they're leading a normal life in New Springfield - they even adopt a child - but it seems they have been guided there for a reason. As rumours of strange sightings and hauntings proliferate, it becomes clear that something is very awry with this particular world. Millions of steps away, Joshua is on a personal journey of discovery: learning about the father he never knew and a secret family history. But then he receives a summons from New Springfield. Lobsang now understands the enormity of what's taking place beneath the surface of his earth - 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 . . .