A millionaire is found murdered in his apartment. Suspicion falls on a variety of suspects, including his fiancé and her parents, the butler, and a professional mentalist known as The Great Gambini.
In this grim story, three murders of young girls are committed in a similar manner, and their bodies are all found in the woods. The only suspect, a young man assumed to be a pedophile, commits suicide during the investigation. A policeman becomes obsessed with solving the mystery of this serial killer and he continues to investigate even after he has been taken off the case.
A novel by Gaston Leroux (of Phantom of the Opera fame) was the source for this film. The story takes place on the Riviera, where the title character may or may not be involved in various shades of skullduggery, including murder. The film’s highlight involves a coffin containing the body of a man who committed suicide — or, did he? Huguette Duflos played the title character, while the comedy relief was in the capable hands of Belieres. In emulation of the 1928 American film The Terror, the opening credits are not printed on screen, but instead spoken by a mysterious “ghost” voice.