The Rough Riders, led by Marshal Buck Roberts (Buck Jones), are on the trail of cattle rustlers when they discover a family of ranchers that has been murdered. A note Roberts finds identifies rustler Bill Cook (John Merton) as one of those responsible. To investigate, Roberts travels undercover, posing as wanted outlaw Bob "Brodie" Bronson. Marshal McCall (Tim McCoy) pretends he is chasing him, but they are actually in cahoots. The two lawmen hope the strategy will expose the real outlaws.