The freshly graduated psychiatrist David shall deliver an opinion about young Maddalena, who's on trial for murdering a hunter. She claims she's a witch and acted on behalf of the devil. The public health officer tells David, he's got reason to believe her, that she'd been searching for a man who suits her needs for 300 years. Already after his first meeting with Maddalena, David begins to change: He ignores his beautiful young wife Cristina and loses himself in daydreams and hallucinations in which he participates in Inquisition questioning and erotic witches' circles.