Two swindlers, Allen (Joe Sawyer) and Flood (Murray Alper), posing as motion pictures producers, are selling fake stock in a movie and inducing the citizens of Sage City to invest their savings in a phony film which they say will star John Wayne. When Gene Autry (Gene Autry) and Frog Millhouse (Smiley Burnette) discover the producers are phony, they trail the pair to Mexico with the aid of their friend and reformed Mexican ex-bandit Pancho Grande (Harold Huber). There the trio suspects Allen and Flood's cohorts, Gibson (Sidney Blackmier) and Homer Gerard (Arthur Loft) are about to pull the same swindler on Don Carlos Alvarado (Julian Rivero), a wealthy, well-respected citizen of San Ramon who has agreed to finance the swindlers' movie in exchange for a role in the film for his daughter Maria Elena (Fay McKenzie). She falls in love with Gene who warns her about the dishonest promoters.
