Horse owner Beaver Greenway is angry when Thunderhead, the white stallion that owner Ken McLaughlin freed some years earlier, steals another of his mares. Greenway confronts Ken's father, Rob, at the Goose Bar Ranch. Rob organizes other ranchers to hunt for Thunderhead who, like his great-grandsire the Albino before him, has stolen many mares from local ranches. Meanwhile, Ken returns from a horse-selling trip but, to Rob's displeasure, has used the profits to buy a
trotter race horse named Crown Jewel. After his initial skepticism, Rob allows the mare to be trained for harness racing. One night, Thunderhead appears and runs off with Crown Jewel. The next day, Rob leads a search party to find Crown Jewel and shoot Thunderhead, though Ken is determined to save him. They locate and round-up Thunderhead's herd, but the stallion and Crown Jewel escape. Ken finds the pair hiding nearby and persuades Thunderhead to return to the ranch for good. When Crown Jewel develops
altitude sickness from living in the Wyoming hills, a veterinarian advises putting her down due to congested lungs; Greenway instead recommends an old-fashioned remedy that works. Meanwhile, Ken and Greenway's granddaughter, Carey, develop a romance. Crown Jewel, fully recovered and trained, is entered in the Ohio Governor's Cup sweepstakes. Greenway, a former
sulky driver is competing with his own horse, Sundance. Ken drives Crown Jewel, who is leading, but she breaks stride during the race, disqualifying them. Greenway and Sundance win. However, the McLaughlins are proud of Crown Jewel's effort, particularly upon learning she is in foal and Thunderhead is the sire. ==Cast==