A sudden, catastrophic nuclear attack devastates New York City, forcing a group of survivors to take refuge in the basement of their apartment building. The basement, previously designed as a fallout shelter by the building's superintendent, Mickey, becomes a claustrophobic sanctuary as the survivors barricade themselves against the unknown dangers outside. As the group adapts to their new reality, tensions quickly surface. Concerns over dwindling supplies, the lack of communication with the outside world, and personal grievances lead to mistrust and paranoia among the nine individuals confined together.

Interpersonal conflicts escalate as basic human civility erodes under the weight of fear and desperation. Mickey's authoritarian control over the resources and his bunker rules adds to the friction, especially as some members of the group start exhibiting aggressive and erratic behavior. The ethical boundaries begin to blur, resulting in power struggles and violence. With no clear leadership and dwindling hope, the survivors grapple with their primal instincts. They face not only the external threat of the nuclear fallout but also the internal threat of their collapsing social order and sanity.