Young Daniel Boone Trewick, caught with a young woman, flees Missouri believing he has killed the girl's father in a fight. He joins a freighting outfit on the Santa Fe Trail, and in Taos he meets Thomas L. "Pegleg" Smith and is invited to join an expedition to California to steal horses and mules. Meanwhile in California, Juan Medina, a young vaquero in trouble for consorting with the ranch owner's daughter, is framed and jailed. After the ladrones steal some three thousand horses and mules, Juan is pressed into service in a posse pursuing the thieves. A thousand horses die from thirst and over-exertion in the Mojave Desert. In a fight with the man who had him jailed, Juan kills his attacker, abandons the posse, joins the thieves and befriends Boone. Boone hatches a plan to turn his share of the stolen animals into a profitable future and invites his friend Juan to join him. Based on a historic horse-stealing adventure.