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.
| Actor | Role |
|---|---|
 Frank MayoClamp | Clamp |
 Ora CarewDiana | Diana |
 Ora DevereauxLeontine de Vallignac | Leontine de Vallignac |
 Harold MillerJames Kirkland | James Kirkland |
 Dagmar GodowskyPatricia Melton | Patricia Melton |
 Bonnie HillMarquise d'Irancy | Marquise d'Irancy |
| FFlora HollisterNot listed | Not listed |
| TTruman Van DykeNot listed | Not listed |
| RRay RipleyNot listed | Not listed |
 Esther RalstonNot listed | Not listed |