In a ruined and toxic landscape, within a giant underground silo hundreds of stories deep, lives a society full of regulations they believe are meant to protect them. Then Sheriff Holston, who has unwaveringly upheld the silo's rules for years, breaks the greatest taboo of all: He asks to go outside. His decision unleashes a drastic series of events. His unlikely replacement - Juliette, a mechanic with no training in law, is about to learn how badly...

From the wreckage of a research facility in Switzerland, a plume of toxic smoke and ash pours into the sky, forming an impenetrable cloud that is slowly smothering the world in darkness. As Europe disappears beneath the Cloud, a squad of United States marines are sent on a desperate mission to find out what went wrong, and how to undo it before it's too late. Venturing into a cold, dark world, the marines must travel deep under the Cloud, with no...