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.
Frank Mayo
as Clamp
Ora Carew
as Diana
Ora Devereaux
as Leontine de Vallignac
Harold Miller
as James Kirkland
Dagmar Godowsky
as Patricia Melton
Bonnie Hill
as Marquise d'Irancy
