A mysterious evildoer terrifies the French Riviera. That mysterious character, which is hidden under the personality of James Pearce, a diamond-maker, calls himself The Black X. This time, the Black X has noticed the rich jewels of a celebrated singer and, in the company of her henchmen, is preparing to carry out the great robbery.
| Actor | Role |
|---|---|
 Paul MansonNot listed | Not listed |
 Fabienne FabrègesNot listed | Not listed |
 Émile KeppensNot listed | Not listed |
 Valentine PetitNot listed | Not listed |
 Maurice LuguetNot listed | Not listed |