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,...

"Juliette, now mayor of Silo 18, doesn't trust Silo 1, especially its leader, Donald. But in the world of the Silos, there is no black and white--everything is shades of gray. Donald may not be the monster Juliette thinks he is, and may in fact be key to humanity's continued survival. But can they work together long enough to succeed?"--

The outer crust is under attack by the subterranean Styx who are turning ordinary humans into walking bombs and incubators for their eggs, and only Will Burrows and his band of retired commandos stand in their way--but the Styx also have problems of their own.