Dr. Dan Potter is a psychiatrist who has recently joined the staff at an experimental mental hospital in New Jersey, run by the eccentric Dr. Leo Bain. This facility employs an unconventional approach, allowing certain patients, referred to as "The Bleeders," more freedom than typically seen in psychiatric care. The asylum houses four dangerously psychotic patients: Frank Hawkes, a former POW who becomes delusionally paranoid; Byron Sutcliff, an arsonist and ex-preacher with a penchant for violent outbursts; Ronald Elster, a child molester and brutal murderer driven by depraved impulses; and John "The Bleeder" Skaggs, a nearly silent killer whose psychosis manifests in unpredictable ways. The patients become convinced that Dr. Potter has killed their former doctor and seek revenge.

During a citywide blackout caused by an electrical worker's strike, the security systems fail, allowing these four dangerous men to escape into the night. They quickly converge on Dr. Potter's home with malevolent intents. As the night progresses into terror, Dr. Potter and his family find themselves under siege. The situation escalates as the danger outside intensifies, leaving them with limited options for safety or rescue. Meanwhile, tension within the asylum itself rises as Dr. Bain grapples with the reality of the dangerous escape. Throughout this harrowing event, the boundaries between insanity and sanity blur, testing the resolve of everyone involved in a suspenseful struggle for survival.