While picking up a shipment of Gatling guns in the town of Willcox, army sergeant Hasty Jones is questioned by a young boy named Danny Reeves. After he tells the curious Danny that the newly invented guns are to be taken to nearby Fort Winston, Hasty meets up with cowboy friends Tim Holt and Chito Rafferty. Tim and Chito have come to Willcox in response to a letter from Hasty and agree to become his partners in a ranch he has just purchased for his impending army retirement. While Tim and Chito ride to inspect Hasty's ranch, Hasty, his men and Judy Davis, the colonel's daughter, drive the loaded wagons toward Fort Winston. On the way, they are flagged down by Danny, who claims to be stranded and begs for a ride. At Judy's insistence, Hasty breaks army regulations and offers the boy a ride to his ranch. Soon after Hasty turns off the main road, however, the wagons are ambushed by a gang of gunrunners, with whom Danny is in cahoots. During the ensuing gunfight, Hasty is wounded and another soldier is killed. Hearing shots in the distance, Tim and Chito ride to the scene, but are unable to stop the gang from stealing the wagons. The gunrunners, who are led by Danny's older brother Steve and Steve's vicious partner Dodge, hide the wagons in a ranch barn. Later, in town, Tim and Chito learn of Danny's treachery and enlist the sheriff to form a posse to search for the stolen wagons. As they comb the canyon, Tim and Chito see Danny, who had been sent to Willcox to spy on them, riding nearby and follow him to the ranch hideout. After Danny reports the posse's activities to Steve, Tim and Chito stage a surprise attack, which leads to Steve's and Danny's arrest. When Steve refuses to reveal the guns's location, however, Tim convinces the sheriff to release Danny to his custody in the hope that he will reform once away from his brother's bad influence. At Hasty's ranch, Danny resists Chito's attempts to bathe him and refuses to say a word about the guns to Tim. Hasty, meanwhile, is court-martialed by Judy's father and is dishonorably discharged. Feeling responsible for Hasty's plight, Judy denounces her father and declares that she is going to fight to have the sergeant re-instated. Later, she tells Tim that she has written to the Secretary of War, confessing her part in the ambush. Judy, Tim, Hasty and Chito then undertake to re-educate Danny and begin by forcing him into the bathtub. Danny's reformation becomes complete when, on his birthday, Hasty returns his favorite dog and horse to him and declares that keeping him on the "right trail" is most important job he could ever have. That same day, however, Dodge finds Danny at Hasty's ranch and tells him that Steve is being extradicted to Mexico and will be executed there. Dodge convinces the boy to intercept the stagecoach carrying Steve in order to say a final goodbye to him. As Danny embraces Steve in the road, Dodge and the gang attack the stage and free their leader. Later, a disconsolate Danny runs away from Hasty's ranch, but is followed to the gang's hideout by Tim, who then discovers the wagons in the barn. After Danny saves Tim from Dodge's bullet, he convinces the cowboy that he was an unwitting accomplice in Steve's escape. As Tim fights the gang from inside the barn, Danny is shot by Steve while riding for help. The wounded boy alerts Chito and the sheriff's posse, who then rescue Tim and arrest Steve. With the guns's return, Hasty is fully reinstated by Col. Davis, and a proud Danny declares that he wants to go to military school and be a soldier some day.