Bluebeard casts the saturnine John Carradine as Gaston, a popular painter in 19th century Paris. Unbeknownst to the authorities, Gaston is also the serial killer of beautiful young women who they have been seeking for several months. Whenever a girl fails to come up to Gaston's standards of perfection, she is summarily strangled to death. Gaston's latest model is the gorgeous Lucille (Jean Parker), who once she learns her employer's horrible secret courageously vows to bring him to justice.