Vogel, a newspaperman, works for a scandal sheet, whose editor in chief, Raymond Bordier, flirts with his secretary, Ann. Raymond and Ann use the castle of a count and countess to organize "Black Masses" with tortures that are so well simulated that the illusion of reality is complete. Their guests appreciate the excitement which is offered to them. Vogel, a former priest and a strange, paranoiac, mystical religious fanatic, walks by accident into one of these festivities. Believing he has witnessed the real thing he decides to exorcize the participants so as to make them confess that they are under the influence of Satan. To obtain this confession, he tortures them to death according to Medieval rites. Only Ann, whom Vogel is madly in love can escape death.