In a ruined and toxic landscape, a community exists in a giant silo underground, hundreds of stories deep. In a society full of regulations meant to protect the community, Sheriff Holston, unexpectedly breaks the greatest taboo of all: he asks to go outside. An unlikely candidate is appointed to replace him: Juliette, a mechanic with no training in law, whose special knack is fixing machines. Now Juliette is about to be entrusted with fixing her silo, and she will soon learn just how badly her world is broken ...