Suppose there were an infinite succession of Earths, and travel between them was as easy as taking a step. A new age for humanity begins when a reclusive scientist posts plans for a “Stepper” online, a relatively simple piece of machinery that is remarkable only for the potato it uses as a power source. Suddenly, the borders of states are irrelevant, and the very idea of scarcity is outmoded. Travel to the other Earths has few limits: iron can’t make the passage, and stepping between worlds induces nausea for most. But not for Joshua Valentine, a strange boy raised in an orphanage by nuns who “read Carl Sagan before they read Genesis”. When a globe-spanning corporation of infinite power and aggressive curiosity decides to launch a mission into the “Long Earth”, the chain of infinite planets humanity is now spreading into, they come to Joshua for help.
The Long Earth has a lot going for it, particularly the titular setting, which tickles the readers' fancy with Earths-that-might-have-been, alternative natural histories. A step away, and the differences are slight: absent of humans, the Americas are still wild and home to megafauna that seem otherwordly to 21st century. In more distant Earths, evolution has taken wildly divergent courses from what Joshua would consider 'normal'. Deep into the long Earth, there are strange and inhuman intelligences, and something is driving those that can step across the earths forward -- toward the datum, and away from danger. Joshua and his companions choose to probe further into the darkness, to confront whatever lays beyond them. Throughout most of the book, his only only traveling companion is a sentient AI named Lobsang who claims to be housing the soul of a reincarnated Tibetan bicycle repairman -- definitely a quirky sort. Fate seems to be an active component of the book, as there are hints that Joshua is Bound for Something, the Chosen One. He's an agreeable enough main character, but the setting takes center stage, especially as human society begins evolving in its new boundless universe. The new abundance of resources means that gold is transparently useless; instead, bartering and the exchange of favors are king. With people breaking away into small communities that can sustain themselves through forage and hunting, human history seems to be reversing itself.
The Long Earth ends with the partial end of a journey, but it isn't the end of the story: a second novel is in the works. I'm looking forward to it.