A cowboy tames a wild horse suspected of killing a man, then rides out to find the real culprit.

A gang of thieves breaks into the Gaunt ranch, where they strike one of the ranch hands and try to steal a horse. After the gang makes its getaway, the leader, Sims, stays behind. Although he is really a notorious murderer known as "The Hawk," most of the townspeople know Sims as a good citizen. He claims that Duke, a spirited horse, was responsible for wounding the ranch hand. The townspeople are about to kill Duke, when John Drury rides into town and stops them. He convinces them to agree that if he can ride Duke, they will not kill him. Over Sims's objections, John rides Duke and the horse is saved. At a meeting of vigilantes, John volunteers to track down The Hawk, and Sims agrees to show him The Hawk's hideout. After Ruth Gaunt warns John about The Hawk, who killed her father, Sims and John ride into the desert, where Sims reveals himself as The Hawk and leaves John and Duke to die. That night, The Hawk's gang burns down the Gordon ranch and leaves John's harmonica behind in order to throw suspicion on John. When the vigilantes find the harmonica at the Gordon ranch, they ride off in search of John, who has escaped from the desert with Duke's help. Meanwhile, Ruth nurses her wounded ranch hand, who recovers consciousness and names Sims as The Hawk. Ruth then rushes off to save John. She tells her story to the vigilantes, who have captured John and are now holding a trial, but no one believes her until Sims's men break into the courtroom looking for their boss. While the posse rounds up the gang, John rides after Sims who has kidnapped Ruth and escaped. Duke corners Sims and finally has revenge on the man who tried to have him killed.