Ever since the war, the world has been divided. Each Class has changed their names and separated into the Water, Earth, and Sky Dwellers. Everyone has decided that this is how it should be... except orphan Marley Gearlock. She's going to get to the bottom of things. Why can't anyone admit that this way of life is wrong? Why is her twin brother acting so strange? What secrets are hiding in the only world she's ever known?