Black Exorcism of Coffin Joe

José Mojica Marins, a director of horror films about the diabolical Coffin Joe, is spending Christmas with friends. Household members go violently mad for no reason: first grandpa, then the hosts' daughters, one of whom, Vilma, is about to get married. Mojica discovers that Vilma's mother made a pact with a witch in order to become pregnant with Vilma, promising this first-born child to Satan; her impending marriage to a human is stirring up things supernatural. It what seems like a dream, Mojica enters a bacchanal in which an entranced Vilma is about to wed to Satan's son; the master of ceremonies is none other than Coffin Joe. Can Mojica defeat his own creation and save Vilma?