In a ruined and toxic landscape, 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