A devastating nuclear attack thrusts nine strangers together in the bunker-like basement of their New York apartment building. The survivors are trapped underground with no hope of rescue, and only horror on the other side of the door. As supplies dwindle and tempers flare, they become increasingly unhinged by the close quarters and hopelessness of their situation, and turn on one another. Still, one survivor holds on to a thin chance for escape, even though salvation is unlikely.