Pepper is a rambunctious big man, minor-league troublemaker, working-class hero (in his own mind), and, suddenly, the surprised inmate of a budget-strapped mental institution in Queens, New York. He's not mentally ill, but that doesn't seem to matter. He is accused of a crime he can't quite square with his memory. In the darkness of his room on his first night, he's visited by a terrifying creature with the body of an old man and the head of a bison who nearly kills him before being hustled away by the hospital staff. It's no delusion: The other patients confirm that a hungry devil roams the hallways when the sun goes down. Pepper rallies three other inmates in a plot to fight back: Dorry, an octogenarian schizophrenic who's been on the ward for decades and knows all its secrets; Coffee, an African immigrant with severe OCD, who tries desperately to send alarms to the outside world; and Loochie, a bipolar teenage girl who acts as the group's enforcer. Battling the pill-pushing staff, one another, and their own minds, they try to kill the monster that's stalking them. But can the Devil die?