Sonny Holman rides into the sunbaked town of Helada carrying a thousand-dollar price on his head for a stagecoach robbery he didn't commit, framed by a treacherous half-brother. Seeking a fiery mount to aid his long search, he successfully tames Gunpowder, a notoriously vicious horse that no one else could ride. Impressed by his grit, the local sheriff, who is himself falsely accused of masterminding a wave of cattle rustling, swears Sonny in as a deputy to help restore order. The townspeople, led by a wealthy rancher named Caldwell and four hostile brothers named Jackson, suspect that the sheriff and his new deputy are in cahoots with the thieves. As tension mounts and unknown gunmen try to eliminate Sonny from the shadows, the danger escalates into open hostility.
Working quietly behind the scenes, Sonny uncovers the truth about the rustlers. The Jackson brothers, who own the Double H ranch, are the actual masterminds behind the stolen cattle and the frame-up against the sheriff. One of the brothers stole the sheriff's carbine to assassinate Sonny, but Sonny anticipates the trap by plugging the rifle barrel with mud before the attempt. During a tense town meeting at the Jackrabbit saloon, the rifle explodes in the sniper's hands, shattering the weapon and exposing the conspiracy to the entire community.
Confronted with undeniable proof of their crimes, the Jackson brothers are subdued, and Caldwell publicly apologizes to the sheriff for the wrongful accusations. The true nature of the rustling ring is laid bare, restoring the sheriff's reputation and bringing a measure of genuine law to Helada. With the local crisis resolved, the sheriff hands Sonny the reward mail containing his own wanted poster, choosing to ignore it out of respect for his deputy's integrity.
Choosing not to reveal his true identity or settle down, Sonny quietly prepares to leave town. He refuses Caldwell's offer of a permanent job on the Lazy L ranch, remaining focused on his ultimate goal of tracking down his treacherous half-brother. Mounting Gunpowder once more, Sonny rides out into the moonlit desert to continue his relentless search, leaving the town behind him.
