The Long Earth involves an improbable invention, an astounding discovery and a journey to see how far the rabbit hole goes. The story begins with two people who have a strange experience where they are transported to some strange location. One is a soldier during World War One in France, and the other is a pregnant teenager, who dies shortly after giving birth.
With the presence of these alternate Earths (all of them apparently empty of human life), a kind of colonization boom occurs. This is not something some world leaders are very appreciative of; a few try to regulate travel, a few try to outlaw steppers. In addition, it turns out that a percentage of the population is completely unable to step, and this percentage begins to engage in the kind of activism that involves bombs. (They believe that if the ability to step is a stage in evolution, then people who can step are not human, or something like that.)
Our protagonist Joshua Valienté, a young man who is famous for being one of the first people to use a device called “the stepper,” when he was a kid. This device enables people to “step” into alternate versions of Earth, one Earth at a time in two arbitrary directions referred to as “East” and “West.” Joshua is primarily famous for having brought back a large number of children who had managed to get themselves in over their head (mostly because they had not followed the directions). Later he becomes famous as a kind of Daniel Boone figure (he really resents the comparison though).
Joshua is hired to serve as a kind of guide or assistant to Lobsang, an AI program that was legally declared human. (He claims to be the reincarnation of a Tibetan motorcycle repairman.) Lobsang is going to be going on a journey into the “High Meggers,” Earths more than a million worlds away from “Datum Earth.” They travel West in an airship (actually, Lobsang is the airship, since he is a computer program) and explore distant Earths and encounter strange creatures, including other hominids with the ability to step. Their journey becomes a quest to discover what is causing a panic-filled mass migration of various hominid species heading East toward Datum Earth.
I sped through this book in a couple hours, both because it was fast paced and because I could not put it down for more than a minute. This is a book with a lot of really great world building and interesting characters. The narrative is engaging, with a great deal of Pratchett’s signature humor worked in. The ending is shocker that is simultaneously horrifying and uplifting. (Horrifying because it involves a disaster, uplifting because of the way people chose to respond to the disaster.)