Steve Bolton, a Department of the Interior agent, has given young "Bronc" Masters a lease to 50,000 acres of range land. Several months later "Bronc" discovers a strange notice on the land, warning off trespassers. He thinks that Steve has leased the same land twice, grabs a gun and heads for town, although his level-headed girl friend, Ann Bradford, attempts to stop him. Steve pacifies him, and they both ride out to the range and discover a gang of men, led by "Spud" Henry, rounding up the wild horses. Henry produces a paper, similar to the one Steve gave "Bronc" and signed by the Secretary of the Interior, and Steve, knowing the paper is a forgery, slaps an injunction on the land, forbidding any horses to be rounded up until the matter is cleared. Henry has had a cleaver counterfeiter forge the signature and knows he will be found out, so he orders his men to rustle the horses and run them to the railroad siding for shipment. But the Durango Kid takes a hand.