Retired gem merchant Peter J. Martin hires detective Dan McRae to guard a large diamond which he plans to present to his daughter Ruth on her twenty-first birthday. Notorious jewel thief Gentleman Joe overpowers McRae, however, and takes his place at Ruth's party.
| Actor | Role |
|---|---|
 Harry CareyGentleman Joe, the Cracksman | Gentleman Joe, the Cracksman |
| EE.A. LockeThe Uncle | The Uncle |
| RRexford BurnettHarold Martin | Harold Martin |
| FFern FosterHarold's Sister | Harold's Sister |
| HHerbert RussellCaptain Dan McRae | Captain Dan McRae |
| MMarjorie BrennerViolet Dane | Violet Dane |
 Juliette DayJune Day | June Day |
| LLouis MorrellRobert Kendall | Robert Kendall |
| WWilliam H. PowerNicholas Moses | Nicholas Moses |
| GGregory AllenOfficer Jim Buckley | Officer Jim Buckley |
 Rolando de CastroRedman Day | Redman Day |
 Hayward MackDistrict Attorney | District Attorney |