At a party thrown at the Metcalf estate, the Marquise D'Irancy's Sultana diamond disappears when the lights go out during a power failure. Suspected of the crime is William Kirkland, the wastrel son of the wealthy Kirkland family, but William's sister Diana comes to his defense. Aiding her in the investigation is Clamp, a wandering peddler.

• Universal Film Manufacturing Company
• Frank Mayo
• Ora Carew
• Ora Devereaux
• Harold Miller
• Dagmar Godowsky
• Bonnie Hill