Synopsis: Jess Franco directs and stars in this shocking thriller of a depraved religious fanatic. A Catholic priest, defrocked for the severity of his beliefs, writes for a French sex magazine. His editor praises his stories for their vivid erotic cruelty, which the author claims is based on "real-life experience." When the priest witnesses a series of staged Black Masses - complete with phony human sacrifices - he becomes convinced that the participants are possessed by spiritual evil and he dedicates himself to cutting the spirit of Satan from their hearts with "the Sword of the Lord." He hunts the unsuspecting victims one by one… "cleansing" their souls of the Devil's dark influence.