On his first day on the job, prison officer Juan Olivier is knocked unconscious in a freak accident and his co-workers carry him to an empty cell. When he awakens, Juan discovers that he has been abandoned in the middle of a riot in a high-security cellblock, home to the prison's most dangerous criminals. If they discover he's a guard, he's dead meat. To survive, Juan must pose as a prisoner and conspire with the riot's vicious leader, Malamadre.