Paris, 1975. After a series of anonymous threatening phone calls, Nora Elmer falls from the top floor of the apartment building where she lives. Her death is investigated by Commissioner Jean Letellier, who soon receives a mysterious phone call from a certain Minos. The man says that he wants to free Paris from licentious women. When Letellier learns that other young women have recently been threatened, he realizes he is dealing with a maniacal serial killer.