In a ruined and toxic future, a community exists in a giant silo underground, hundreds of stories deep. There, men and women live in a society full of regulations they believe are meant to protect them. Sheriff Holston, who has unwaveringly upheld the silo's rules for years, unexpectedly breaks the greatest taboo of all: He asks to go outside. His fateful decision unleashes a drastic series of events. An unlikely candidate is appointed to replace...

Armed with secret knowledge, Juliette, now mayor of Silo 18 and her crew set out to rescue a world she hates but now understands better -- the world of the Silos with its rigid rules and terrible consequences for disobedience.