Hoppy and his pals arrive in a remote town to investigate the counterfeiting of both U.S. and Mexican money; his only clues are the name "Mordigan" and a drawing of a comet. He quickly finds out that Mordigan is the town "boss"; but what or who is "the comet", and why are Mordigan and his henchmen intent on persecuting a young woman, her drunken brother, and her deathly ill sister-in-law who've also just arrived in town?
| Actor | Role |
|---|---|
 William BoydHopalong Cassidy | Hopalong Cassidy |
 Andy ClydeCalifornia Carlson | California Carlson |
 Rand BrooksLucky Jenkins | Lucky Jenkins |
 Elaine RileyNora Murray | Nora Murray |
 James CravenMordigan | Mordigan |
 Robert B. WilliamsHenchman Pete Walters | Henchman Pete Walters |
 Alberto MorinRamon De Lara, faro dealer | Ramon De Lara, faro dealer |
 Joel FriedkinDr. White | Dr. White |
 Francis McDonaldHenchman Longhorn | Henchman Longhorn |
 Lee Tung FooWong | Wong |
 Herbert RawlinsonJohn Murray | John Murray |
| WWilliam F. LeicesterSid Murray | Sid Murray |
 Joan BartonMary Murray | Mary Murray |
 Dewey RobinsonJoe, the bartender | Joe, the bartender |