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,...

Six months after vanishing into an underground silo with sixty others, Wynter and Chase emerge to find the area abandoned. There is no sign of Noah and the rest of the group that was supposed to greet them when they emerged--the same people Wynter was counting on to help her locate the IV antibiotics her gravely ill friend, Julie, needs in order to live. As the clock ticks down on Julie's life, Wynter and Chase embark on a desperate search for medicine...