The story of an eleven year old boy whose one intense desire is that he have a colt of his own. The whole action of the story takes place against the pattern of a ranch devoted to raising blooded horses, out in Wyoming. At last his wish is granted, and he chooses his yearling, against all advice. The story is centered on the process of winning 'Flicka' and of proving the rightness of his choice.

Ken McLaughlin's mare, Flicka, give birth to an ugly white colt that Ken's mother names Thunderhead. It becomes clear as Thunderhead grows that he possesses unusual capacties of strength, speed, and intelligence. The young stallion becomes an incomparabel racehorse, king of a wild brood of horses and the center of an absorbing story of adventure in the mountains and plains of Wyoming.

Based on the author's musical "The catch colt." Letty's parents refuse to allow her to marry a cowpuncher unless he can find out who his parents are.