Bob Hill and Thad Grove, two prospectors, find a small child in the desert cabin of bandit Sonora Jack. The little girl, Marta, who has been kidnapped by Jack, is taken by the men, who vainly attempt to find her parents. Marta grows to womanhood and falls in love with Hugh Edwards, a young fugitive from justice. Edwards saves Natachee, an educated Indian, from the depredations of a bandit gang, and in return the grateful Indian shows Edwards the location of the "mine with the iron door," a hidden and extremely rich gold mine. Sonora Jack returns and kidnaps Marta, offering to exchange her for knowledge of the location of the "mine with the iron door." Edwards and Natachee go after the bandit and kill him while saving Marta. Edwards is proved to be innocent of the charge of embezzlement placed against him, and he and Marta are married.