John Carradine stars as Gaston, a successful nineteenth century artist and puppeteer in France's capital. Gaston, however, lives a secret life as Bluebeard, a demented serial killer who coldly strangles a series of beautiful young women who fail to meet his impossible standards. The lifeless bodies are discarded in the Parisian streets. All is concealed from the authorities until Lucille (Jean Parker), Gaston's comely assistant, learns the awful truth and swears to bring him to his day of reckoning.