Before The Shadow and his gang of outlaws execute a stagecoach robbery, John Travers, a United States Marshal, and his Indian friend Yak intercept the coach and rob it themselves. Two of The Shadow's henchmen brutally murder the coach's driver and guard, and the horses bolt and run away with the coach. Travers saves passenger Anita Matlock, who is on her way to claim the ranch left to her by her recently murdered father, and escorts the coach into the town of Little Rock. Soon after the coach arrives, the sheriff is shot and killed, and Travers learns from Matlock, Anita's uncle and a respected rancher, that Little Rock's two previous sheriffs also were murdered. With the help of Yak, Travers begins an investigation and discovers that the killer's instructions are coming from a voice behind a phony safe in the saloon. Travers and Yak follow the gunmen and find a hideout that is near Matlock's ranch, full of notorious outlaws. After warning Matlock and Anita, who is visiting her uncle for the first time, about the outlaws, Travers and Yak jail two of The Shadow's men. That night, they further investigate the saloon, finding a secret tunnel that leads to a hollow stump in the middle of the main street. Anita, meanwhile, learns from a ranch hand named Jake that Matlock is The Shadow and that he killed her father and uncle and has assumed her uncle's identity. She tries to warn Travers, but is taken hostage by the gang as they head for town with a machine gun. Travers deputizes the townsmen and, following a daring chase, captures Matlock and the gang. Eventually, Anita and Travers marry.
