Mary Elizabeth Winstead stars as Michelle, who is leaving her fiancé, Ben voiced by Bradley Cooper), after an apparent deal-breaking disagreement that he must feel sorry for, given that he is persistently calling as she's on the rural Louisiana road heading out of town.  That's the last thing she remembers, as Michelle end up in a car accident that sees her roll off the road and take a nasty tumble.  When Michelle awakens, she finds herself in a strange bed with an IV in her, chained to the wall and enclosed in a nearly empty room with a dense-looking metal door that's locked tight. She's soon visited by an armed man named Howard who claims to have saved her life, claiming that they're the only ones left alive in their fallout shelter, and that everyone outside is likely dead or dying due to an apocalyptic event that has poisoned the air.  There's enough in the mini-bunker to keep them fed and secure for years, but is Howard, an avowed conspiracy nut, a benign Samaritan, or is he her captor, trying to keep her from escaping his lair for reasons too horrific to contemplate?