A veteran hostage negotiator's next call leads him to an overrun mental hospital. He soon finds that dark forces are pushing the patients to commit atrocities, and he could be the only one that can stop them.

An 11-person riot squad races to a psychiatric hospital to quell a recent inmate outbreak and hostage situation. When they arrive, they are caught off-guard by a sudden barrage of insane patients. When they've finally fought off the wave, two of their squad members are missing, their communications return only static, and the doors are locked: they are trapped. They break up into three teams to track down the lost members. Strange sounds and religious iconography suggest that something beyond insanity has taken over the inmates. Sure enough, a simple rescue mission quickly morphs into relentless life or death battles with possessed beings. When McGahey, a trained, rational hostage negotiator, discovers that the ringleader of this possessed insanity is none other than his brother, it falls on him to stop nothing less than the opening of a portal to Hell.—Gage Oxley