Cowboy Serenade.

Gene Autry heads a cattlemen's association and calls on the inexperienced Jim Agnew to negotiate the sale of five hundred heads of cattle. Jim ends up losing the cattle in a crooked poker game, however, and Gene and his sidekick Frog set out to find the cheating gamblers. It soon becomes clear that the leader of the gamblers is none other than Asa Lock, the dastardly father of Gene's romantic interest Stephanie.