The night before a local haunted house opens for Halloween, six friends sneak in for a few hours of fun. Soon after entering, they find themselves trapped inside with no way out. Their evening of fun rapidly turns into their worst nightmare as they begin to die and disappear in the most freakish of manners. With every effort to escape blocked, the survivors find themselves being driven deeper into the carnivalesque world of terror. Unable to tell what is real and what is counterfeit, they must trust one another, even if it kills them.