A man has kidnaped an engraver and has him forging Mexican bills. He captures wild horses supposedly to sell for hides but uses them to transport the bills across the border. Police captain Juan Reyes (Richard Avonde) is posing as a bandit to uncover the counterfeiters smuggling fake pesos into Mexico, and is assisted by feisty youngsters Red (Michael Chapin) and Judy (Eilene Janssen), who are trying to protect the wild horses being used by the gang. The kids suspect that rancher Big John Harkins (Roy Barcroft) is the leader of the gang and that he is forcing Mexican artist Espinosa (Julian Rivero) to help him.

After conning a potential buyer into believing that Queenie's herd is diseased, nasty would-be empire builder Duke Drake is confronted by the girl's new tough foreman Bill Foster. In retaliation, Drake frames Bill for a stage robbery committed by his own henchmen and arranges a phony trial presided over by the saloon's bartender Judge Whipple. Queenie interrupts the "trial" with the news that the townswomen have all elected Jim Marshal. To uphold the decision, Bill has secured the release of three convicted outlaws: Blackie Malone, Bad Bill Smith, and Shotgun Thompson, two of whom join in the fight against Drake and his gang.