Det. Michael Turner (Michael Par├й) travels to a maximum security prison to investigate a series of strange murders and suicides. With help from his former partner, Frank Miller (Tom Sizemore), who is now a prison guard; psychiatrist Dr. Ashley Carter (Jenny McShane) ; and some scared prisoners (Ja Rule, Danny Trejo), Turner learns that a demonic spirit living in the prison's furnace is responsible for the deaths. Turner must work fast to put the evil spirit to rest before more inmates die.