1916: The Western Front. Private Percy Blakeney wakes up. He is lying on fresh spring grass. He can hear birdsong and the wind in the leaves. Where have the mud, blood, and blasted landscape of no-man's-land gone? For that matter, where has Percy gone? 2015: Madison, Wisconsin. Police officer Monica Jansson is exploring the burned-out home of a reclusive--some say mad, others allege dangerous--scientist who seems to have vanished. Sifting through the wreckage, Jansson find 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. The "stepper" enables a person using it to step sideways into another America, another wherever that person happened to be, another Earth. And if the person using it keeps on stepping, they keep on entering even more Earths. This is the Long Earth. And the further away a stepper travels, the stranger -- and sometimes more dangerou

1916: The Western Front. Private Percy Blakeney wakes up. He is lying on fresh spring grass. He can hear birdsong and the wind in the leaves. Where have the mud, blood, and blasted landscape of no-man's-land gone? For that matter, where has Percy gone? 2015: Madison, Wisconsin. Police officer Monica Jansson is exploring the burned-out home of a reclusive--some say mad, others allege dangerous--scientist who seems to have vanished. Sifting through the wreckage, Jansson find 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.

A new America called Valhalla grows restless under the controlling long arm of the Datum government, while all of the Long Earth is infused by the song of the trolls who are starting to react to humanity's thoughtless exploitation, bringing humankind to the brink of war.

"After the cataclysmic upheavals of Step Day and the Yellowstone eruption, humanity is spreading further into the Long Earth Society, on a battered Datum Earth and beyond, continues to evolve. And new challenges emerge. Now an elderly and catankerous AI, Lobsang is living with Agnes in an exotic, far-distant world. He's determined to lead a normal life in New Springfield--they even adopt a child. But there are rumors, strange sightings in the sky. On this world, something isn't right ... Millions of steps away--learning about a hidden family history and the father he never knew--Joshua receives an urgent summons from New Springfield. Lobsang has come to understand that what has blighted his Earth is a threat to all the worlds of Long Earth. To counter this threat will require the combined efforts of humankind, machine, and the superintelligent Next. And some must make the ultimate sacrifice ..."--

"The third novel in Terry Pratchett and Stephen Baxter's "Long Earth" series, which Io9 calls "a brilliant science fiction collaboration.""--

Lobsang's pursuit of a human life, Joshua's search for his father and the adaptation efforts of "the Next" post-humans are challenged by a voracious alien race that would conquer and colonize the Long Earth.

It's 2070-71. Nearly six decades after Step Day, and in the Long Earth the new Next posthuman society continues to evolve. For Joshua Valiente, now in his late 60s, 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.