Disgusted when the police department fails to apprehend the murderer of her guardian, Henri Du Bois, Celeste decides to track down the criminal herself. Her only clue is a cuff link dropped near the scene of the crime on which a sphinx is engraved, and with it, she wanders through Paris' tough Moulin Noir district. When she notices a young man wearing a tie pin of identical design, she cultivates his acquaintance and eventually asks him to visit her in her home. His suspicious behavior there con...