Gridley is mining silver from an old Mexican mine and bringing it into the USA thru a passage into his worthless mine. Border guard Rogers suspects Gridley and finally finds the secret entrance to the Mexican mine. He sends Lee Madison for help only to have her captured by Gridley. Trigger brings help that takes care of Gridley's men and now Roy has to rescue Madison.
| Actor | Role |
|---|---|
 Roy RogersRoy Rogers | Roy Rogers |
 TriggerTrigger | Trigger |
 Dale EvansLee Madison | Lee Madison |
 Andy DevineCookie Bullfincher | Cookie Bullfincher |
 John McGuireRex Gridley | Rex Gridley |
 Olaf HyttenLionel Bates | Lionel Bates |
 David SharpeHenchman Ulrich | Henchman Ulrich |
 Fritz LeiberPadre | Padre |
 Hank PattersonDeaf bus passenger | Deaf bus passenger |
 Fred 'Snowflake' ToonesThe Cook | The Cook |
 Eddie AcuffBus Driver | Bus Driver |
 Bob NolanBob | Bob |
 Pat BradyPat | Pat |