Old timer Hank Robbins and his young pal,"Red" Hepner ride into the town of Cajon, Mexico and find it under a reign of terror imposed by a mysterious outlaw known as El Lobo. Don Jose Valencia is also upset over the romance between his son Francisco and saloon girl Dolores. Pete Sangor, an American resident, has his eye on the girl also. "Red" and Hank discover that Sangor is El Lobo, and ride to rescue the kidnapped Francisco.
The railroad wants to extend a line across the Briggs' ranch, and hires a gang to get rid of John Briggs and his daughter, Nan sweetheart of the local sheriff. Wanderers "Sidewinder" Steve and his young friend "Red" Hepner take a hand in the proceedings and manage to save Briggs and his daughter, the ranch, and the romance.