A rich but naive young woman is in possession of some priceless jewels. She herself doesn't know it, but a gang of jewel thieves does.

Pete Pepper is a shy, timid circus performer who is scared to death of horses, but rides like a whirlwind when he has been hypnotized by "Ollie" Finch. Pete is entered as a competitor in a wild-west cross-country obstacle race...and has to ride without being hypnotized.

The U.S. Army needs more horses for the Spanish-American War. Hoppy must turn his Bar 20 cowhands into Rough Riders to gather up the horses, and of course bad guys try to sabotage the operation.