Edgar lives on a mysterious world in which there are three layers- the Highlands, where the rich and powerful live and control the water supply to the whole world; Tabletop, where the working class lives and supplies the Highlanders with food; and the Flatlands, which are barren. It is forbidden to climb the cliffs which separate the lands, but when Edgar was little he remembers a man who he thinks was his father telling him that something special is hidden for Edgar in the cliffs, so Edgar spends all his extra time secretly climbing the cliffs trying to find this special item.

Spoiler

Edgar finds a book hidden in the cliff wall, but he nor anyone from Tabletop can read, as that is forbidden. Edgar climbs to Highlands to find someone who can read the book. He meets another boy, Samuel, whose father used to be a leader but is now missing, presumed dead (rumored to have fallen off the cliff). The book warns that Highlands and Tabletop will sink and the world will all become one level, which makes the Highlanders afraid that the Tabletoppers will revolt and their cushy high-class life will come to an end, and also scary deathly creatures from Flatland will invade and kill the whole planet.

I liked the story, the characters are likable and just enough "evil nemesis" to keep things interesting but not obnoxious. The book ends on several cliffhangers, so it's not a single book but part one of a three-part long story.