A killer of young women, dubbed Bluebeard, is loose in Paris. Lucille and her friends meet Gaston Morrell, a puppeteer. He invites them to a show the next night; they go. Afterwards, he walks with Lucille; she offers to make costumes for his next show, he accepts, and feelings develop that may lead to love. She suspects he has a tragic past. Meanwhile, his leaving the show with Lucille prompts the jealousy of Renee, Gaston's sometime lover. Lucille's younger sister, Francine, comes back to Paris - her boyfriend is Inspector Lefebre, who's hunting for Bluebeard. Some clues point toward Lamart, a greedy art dealer. Who is in danger, and can Gaston be trusted?