| Buster Keaton | The Boy/Sherlock Jr.,Rollo Treadway |
| Kathryn McGuire | The girl,Betsy O'Brien |
| Ward Crane | The Rival |
| Fred Vroom | John O'Brien |
| Jane Connelly | The Mother |
| Clarence Burton | Spy |
| Joe Keaton | The Girl's Father |
| Erwin Connelly | Villain's Henchman |
| H.M. Clugston | Spy |
Technical Credits
| Buster Keaton | Director |
| Donald Crisp | Director |
