It has been 14 years since the Martian invasion. Our technology has taken great leaps forward, thanks to machinery looted from abandoned war-machines and capsules. So when the signs of launches on Mars are seen, there seems little reason to worry. Unless you listen to one man: Walter Jenkins, the narrator of THE WAR OF THE WORLDS. He is sure that the Martians have learned from their defeat, adapted their methods, and now pose a greater threat than ever before. He is right. Thrust into the chaos of a new worldwide invasion, journalist Julie Elphinstone --- Walter Jenkins' sister-in-law --- struggles to survive the war, report on it, and plan a desperate effort that will be humanity’s last chance at survival.

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 this computer the size of an Earth continent, they must obtain help from the more populous and still industrious worlds of mankind. This concluding volume of the Long Earth series explores the greatest question of all: What is the meaning of life?

Human society continues to evolve on Datum Earth as the spread of humanity progresses throughout the many Earths beyond. Lobsang suffers a breakdown and attempts to live a “normal” life on one of the millions of Long Earth worlds. His old friend, Joshua, searches for his father and discovers a heretofore unknown family history. But an alien planet has somehow become “entangled” with one of the Long Earth worlds. As Lobsang and Joshua learn, its voracious denizens intend to capture, conquer and colonize the new universe they have inadvertently discovered.

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 rescue work when Sally is contacted by her long-vanished father. He tells her he is planning a fantastic voyage across the Long Mars and wants her to accompany him. But Sally soon learns that he has an ulterior motive for his request.

A generation after the events of THE LONG EARTH, humankind has spread across the new worlds opened up by “stepping.” A new “America” --- Valhalla --- is emerging more than a million steps from Datum, our Earth. Valhalla is growing restless under the controlling long arm of the Datum government. Soon Joshua Valiente is summoned by Lobsang to deal with a building crisis that threatens to plunge the Long Earth into a war unlike any humankind has waged before.

Police officer Monica Jansson is exploring the burned-out home of a reclusive scientist who seems to have vanished. Sifting through the wreckage, Jansson finds a curious gadget: a box containing some rudimentary wiring, a three-way switch, and…a potato. It is the prototype of an invention that will change the way humankind views the world forever.