As every summer, Alexa Daley is staying in Bridewell with her father while he conducts important political business. But she has decided that this summer will be different: Alexa is bound and determined to find a way outside of the wall that protects the civilized cities from the outside world. And when she does so, she develops the magical ability to speak to animals—and discovers a conspiracy that might just doom the world as she knows it.
Like the other denizens of Tabletop, Atheron’s middle level, eleven-year-old Edgar can’t read. So when he comes across a secret book that was left to him years ago, he has no choice but to climb the almost-sheer cliffs separating Tabletop from the ruling level, the Highlands, in search of someone to read his book to him. There he befriends a quiet, bookish boy named Samuel, who reads in the book the hidden truth behind Atherton’s recent earthquakes – the Highlands are collapsing into Tabletop. As the people of Tabletop discover the treachery of those in power and prepare to make war on the Highlands, Edgar embarks on a desperate journey to the desolate Flatlands, Atherton’s lowest level, where he may find the answer to the mysteries of Atherton’s very existence – and, possibly, its destruction.