Worldshaker

Set on Worldshaker, a massive moving city where wealthy families live on the Upper Decks while the working class, known as Filthies, live Below, the story follows sixteen-year-old Col, who is being groomed to become the next Supreme Commander of the juggernaut. When Riff, a Filthy girl, stows away in his cabin, Col's understanding of his world is challenged as he learns about the lives of the people who keep Worldshaker running. Through his friendship with Riff, Col begins to question the society he was raised to command.