Plagued by a gang of cattle rustlers, the ranchers of Trail City send for ranger Frank Mattison to purge their town of outlaws. While riding the trail one day, rancher Clay Travers witnesses a rider being attacked by bushwackers. Clay gallops to the aid of the wounded man, who identifies himself as Mattison, and with his dying breath, asks Clay to present his money belt to his sister Sally, who is due to arrive on the next stage. Back in town, Mark Kenyon, the head of the cattlemen's association who was secretly in league with the rustlers in planning Mattison's demise, instructs Ed Martin to pose as the ranger. Pretending to be ignorant of the dead man's identity, Clay brings the body to town where, after examining the corpse, the doctor tells Kenyon that an impression in Mattison's skin indicates that he was wearing a money belt that is now missing. When a search of Mattison's papers reveals that his sister Sally is to arrive, Kenyon sends his men to hijack her stagecoach. Realizing that the girl is in danger, Clay and his ranch hand Ike ride to meet the stage and rescue Sally from her attackers. Sally believes that the episode was an elaborate practical joke planned by her brother, and Clay, reluctant to inform her of her Mattison's demise, sends her to his ranch with Ike. Back in town, Kenyon discovers that Clay is in possession of the money belt and decides to eliminate the rancher. After Clay drives the stagecoach into town, Martin demands the money belt and accuses him of working with the rustlers. When Clay denounces the ranger as an impostor, the man explains that Mattison was his partner whose identity he assumed so that his partner could work undercover. Sensing a frame- up, Clay pulls a gun and escapes. Learning that Sally is at Clay's ranch, Kenyon visits her and escorts her to town after informing her that Clay has murdered her brother. Fearing for Sally's safety, Clay tells Ike and his other hands to pretend to quit their jobs, sending them into town to protect Sally. Clay then tracks down the rustlers to their hideout in Hidden Valley. That night, he rides to meet Ike, who has received a reply to his telegram to ranger headquarters that confirms that Martin is an impostor. Armed with the telegram, Clay visits Sally in her hotel room and persuades her that he is on the side of the law. After convincing rancher Frank Curtis that Martin is an impostor, Clay sends the rancher to Kenyon and Martin with news that Clay is holding several rustlers hostage in his bunkhouse. As Frank assembles the other ranchers, Clay rides to his ranch and catches Kenyon and Martin in his trap. Kenyon and his men overpower Clay, however, and ride to Hidden Valley to drive the herd out of the country. Soon after, Frank and the others arrive at the ranch and are joined by Clay, who leads them to the rustlers' hideout. In a blazing shootout, the ranchers apprehend the outlaws and Clay is exonerated. With her brother's killers brought to justice, Sally leaves town on the next stage.