Based on the spy novel of the same name by Jacques Futrelle.
| Actor | Role |
|---|---|
 Florence LawrenceIsabel Thorne | Isabel Thorne |
 Sidney BraceyLuiigi | Luiigi |
 Harry F. MillardeHamilton Grimm | Hamilton Grimm |
 Wallis ClarkPrince D'Abruzzi | Prince D'Abruzzi |
 William WelshChief Campbell | Chief Campbell |
 Paul PanzerCoount Rosini | Coount Rosini |