One day, humanity discovers they can "step" from our world into parallel worlds. Each of these other Earths is slightly different from the next--but humans exist on no other world but our own. Humans immediately start stepping into other worlds to explore and create new homes. Resources and space are no longer scarce; old hierarchies start breaking down.
Joshua Valiente is a natural Stepper, someone who can jump from one world to the next without any ill effects. And so the first AI to be declared sentient (by dint of claiming to be the reincarnation of a Tibetan motorcycle repairman) hires him to be his companion as they explore farther into the alternate Earths than any humans before. Along the way they discover other sentient beings, who discovered stepping earlier in their evolutionary tracks: the peaceful "trolls" who communicate by song and scent, and the scrawny but aggressive "elves". These creatures are migrating toward the original Earth in what can only be called a very slow stampede. Lobsang, Joshua, and their chance-met companion Sally "step" against the stampede, hoping to find out what danger is approaching. And what they find is beyond their wildest imaginations. What scares the trolls and elves, and has been creating a mental pressure that Joshua must fight against, is a singular entity that evolved to be the only sentient creature on its Earth. Rather like the Borg, it envelops and incorporates any creature it comes across; after meeting a troll, it learns to step, and has been stepping toward the original Earth ever since. This sounds both cool and scary, but what's weird is how calmly the characters take it. Lobsang incorporates himself into the creature, and then the humans consider the matter solved, I guess? Even though they have no reason to? For all they know the creature just took Lobsang's HUGE store of knowledge and will use it to get to original Earth even faster, so I don't get why they saunter back home like everything is hunky-dory. And then, in the last two chapters, a nuclear bomb gets set off in original Earth, everyone escapes by stepping, and that's the end of the book. No consequences get explored, no one reacts to it emotionally...it's a very anticlimactic ending despite involving a nuclear bomb.
This was not a good book. The dialog is stilted and made up of info-dumps, the descriptions of alternate Earths repetitive and boring. Various side characters, mostly never heard from again, are given a chapter each to tell the tale of their own exploration. Pratchett's contribution is nearly invisible--there's one section in which a WWI private thinks about his boots and another about a religion that seems Pratchett-esque, but there are few moments of humor and no other moments of whimsy. The characters never seem to really have personalities or connect to each other, and the only character who felt remotely real was Monica Jansson (a lesbian cop who is one of the few people who fully understands what alternate earths means for the original Earth). The pacing is soooo slow, and the plot is basically non-existent. It felt like the authors figured out they needed a plot about four chapters from the end, shoved a couple dangers in, and then went back to what they really wanted to talk about, which was boring characters creating boring homesteads. It's not even fun in a [b:Hatchet|50|Hatchet (Brian's Saga, #1)|Gary Paulsen|http://d.gr-assets.com/books/1347443751s/50.jpg|1158125] kind of way, because there's no struggle to survive--humans settle on worlds so rich in resources that they don't even need to farm; fish practically leap into their baskets. And there's no real world-building; they don't explore how the original Earth changes, or talk further about what it means that Happy Landings has no crime or disabled people, or get in depth about anything at all. It was, in all, very disappointing.