Will James tells the story of a beautiful, strong-spirited horse named Smoky. Smoky is born in Arizona on the range lands belonging to the Rocking R ranch, and his first six months of life are spent happily investigating the countryside. When the colt is six months old, he and the other horses are rounded up for the spring branding. Jeff Nicks, the ranch manager, discusses the horses with his best bronco buster, Clint Peters, who admires Smoky's independent nature. Clint tells his friend, ranch hand Buck, that someday he wants to have something special all to himself. As the next three and a half years pass, Smoky grows to maturity and becomes the leader of the herd. He rescues a filly who is being menaced by a mountain lion, but his freedom is again taken away when another roundup occurs. Clint is determined to break the headstrong Smoky and make him his own. Three months go by as Smoky gradually is taught to accept the bridle and saddle and to trust Clint, whose deep love for the animal distracts him from returning the affections of Betty Jarvis, the college-educated daughter of the ranch's owner. One afternoon, Smoky is spooked by a rabbit while Clint is riding him, and Clint is seriously injured in the resulting fall. Unable to climb back into the saddle, Clint ties his arm to the stirrup, and his faithful horse gently drags him to the ranch, where Buck and Betty tend to his injuries. When Clint recovers, he asks Jeff if he can join the regular cowboys on the ranch, and if he can have Smoky for his own. Jeff agrees, and Smoky and Clint make an impressive team during the next roundup. A mean-spirited half-breed named Lefty claims he can ride Smoky, and when the horse throws him, Clint must restrain him from injuring Smoky. That night, Lefty steals the horses and takes them to a trader, who accepts all except Smoky, whom he states is too wild. Lefty spends weeks beating the animal in an effort to break his spirit, and the horse learns to hate him. Finally, Smoky tramples Lefty and escapes. Meanwhile, Clint searches desperately for his beloved horse, but is forced to give up when Jeff offers him a chance to take over the ranch. Clint proposes to Betty, and the couple begin their life together. Smoky becomes an outlaw who hates and fears all humans, and after being captured, he becomes a star performer in a rodeo that bills him as "The Murder Horse." Riders are promised a $500 reward if they can stay on Smoky, but he always bucks them off. Three years pass as Smoky's spirit and health are broken by hardship, and he is sold to a cruel junkman, who beats the horse when he does not pull the wagon quickly enough. Clint, Betty and their son Junior are in a restaurant when Buck bursts in and tells them that he has just seen Smoky pulling a junk wagon. They chase after the wagon but lose it in the crowd and, after a frantic search, find the junkman just as he is leading Smoky to the slaughterhouse. Clint is overwhelmed to have found Smoky again, and the horse is happy to be found by his old friend. Clint sends Smoky to the ranch, where the animal lives out his days in peace and comfort.