In addition to his duties as executor of an estate Gene must keep a juvenile delinquent from the clutches gambler Feeney who hopes to get at the money through the kid.

As Gene Autry tows a horse trailer down a desert road with his truck, young Randy Pryor shoots at the truck with an air rifle. Gene pulls off the road to investigate, and a troop of students from the New Mexico Military Institute in nearby Roswell ride up on horseback. Goaded by his friend, Gig Jackson, Randy then shoots Chuck Brunton, the captain of the troop, and the cadets, accompanied by Gene, chase the boys. When they finally stop, Gene learns that Randy is the son of his old friend Jim, who recently died after appointing Gene his executor. When Gene arrives at the Pryor ranch, he meets Jim's niece, Eileen MacDonald, who was brought up there. She discloses that Randy has promised to carry nothing more than an air rifle until he is twenty-one, because he has a bad temper. That night, after dinner, Randy joins Gig at the Feeney ranch. After he leaves, Eileen reluctantly tells Gene her belief that Gig, who works at the ranch, has been a bad influence on Randy and has encouraged him to gamble with Pat Feeney. Gene decides to investigate, but when he steps outside, he sees a man leaving the barn in which Randy's prize race horse, Bluebell, is kept and chases him. The man introduces himself as Rufe Burns from the Feeney ranch. Meanwhile, Feeney goads Randy, who has already lost $600, into betting Bluebell in a race against Feeney's best horse, with both horses going to the race's winner. Randy loses the race and Bluebell, and Gene later discovers a piece of rock lodged in Bluebell's hoof. Although Gene suspects that Feeney is responsible, he cannot prove it. Unknown to Gene and Randy, Feeney wants revenge because, years earlier, Jim turned Feeney in for crooked gambling and then married his girl friend. To keep Randy out of further trouble, Gene decides to send him to the New Mexico Military Institute. Randy is prepared to hate the school but, in spite of himself, is impressed by the level of horsemanship that he sees there. Gene then fires Gig and offers to pay off Randy's debts. Feeney refuses to take the money and orders Gene off his ranch. Some time later, the entire Pryor ranch crew, including Gene and Eileen, goes to the military school to watch Randy play polo. During the game, Randy's bad temper causes him to be dismissed from the school. The next day, Gig tells Randy that Burns put the stone in Bluebell's shoe on Feeney's orders. Randy is so mad that he picks a fight with Gig and knocks him unconscious. Seeing the opportunity to get rid of both Gig and Randy, Feeney then kills Gig and blames the murder on Randy. Burns claims to be horrified by the cold-blooded murder and helps Randy escape. Feeney and his men then chase Randy, planning to kill him as well. Later, Gene and Eileen arrive at the Feeney ranch and discover Gig's body. They hear shots, and while Eileen rouses the cadets at the military school, Gene goes to Randy's aid. When Gene tells Randy that Gig was killed by a blow to the skull, Randy realizes that he was not the murderer. Still determined to get revenge, Feeney shoots Randy, but is overcome by Gene. When Randy recovers, he returns to the New Mexico Military Institute a changed man.