In 1880, red-haired Dr. Julia Winslow Garth leaves Boston for a new life, taking with her such innovations as a stethoscope and newly developed theories about antisepsis. Settling near Santa Fe, where her brother, Lt. David Garth, is stationed with the Army, she sets up shop in an adobe house next to a mission church run by Father Gabriel Mendoza and soon receives her first case, a toothache victim brought in by Billy the Kid. A local tomboy, Spurs O'Brien, who is infatuated with David, befriends Julia and sells her a horse and buggy. When Spurs’s widower father, Dr. Rork O’Brien, sees Julia driving the buggy, he chases her through town. When he accuses her of horse theft, she explains to Rork that she bought the horse and buggy. Although Rork is also a physician, his closed-minded opinions about a “woman’s place” and his rejection of new medical techniques keep them from forming a friendship. Father Gabriel shows Julia the hospital he has started, and there she operates and restores the sight of a ten-year-old glaucoma patient. The boy’s father, Bartolo Diaz, proclaims her a saint and praises her to the other townspeople. Despite his professional opposition to Julia, Rork becomes attracted to her and teaches her to ride a horse Western-style. While they are riding, young Apache braves approach, intrigued by Julia's red hair, but leave after the leader touches her hair and Rork claims her as "his woman." When Julia answers a request for a house call, she finds that David, who had years ago promised to stop gambling, has shot a man in self-defense during a poker game at a saloon. Rork is annoyed that many of his patients have turned to Julia and accuses her of having a vindictive need for revenge against male physicians. He insists that she stop working at the hospital, and when she refuses, he quits. At the hospital, Julia has been able to help a physically abused mental patient, Norah Muldoon, but she cannot prevent Norah’s abusive boyfriend from trying to take her away. Rork arrives just in time to prevent the man from removing Norah. Still angry at Julia, Rork avoids her for two weeks. However, after arranging a surprise birthday party for Julia, Rork admits that he missed her, offers her an engagement ring and woos her by quoting a poem by Elizabeth Barrett Browning. Although touched by his romantic streak, Julia declines his offer, saying that marriage could never work between two ruthless, stubborn people. As proof, she admits her obsession with proving herself in a man’s occupation and points out that Rork’s prejudice and arrogance is what she ran away from in Boston. He angrily leaves, but weeks later, escorts her to the Governor’s Ball. Spurs also attends, dressed in a gown that Julia has had made for her, which prompts David, who has told Spurs that he loves her only as a child, to see her in a new light. During the evening, Julia meets the governor, Gen. Lew Wallace, who is writing a novel, Ben Hur . When he mentions that he has chronic heart problems, she suggests that his tight collar might be the source of his problem, unaware that she is contradicting Rork's previous diagnosis. Expecting that his reputation will be harmed by the resulting gossip, Rork becomes angry with Julia. Elsewhere at the ball, David strikes Capt. Taggart, a superior officer who has accused him of cheating at cards and selling stolen cattle to the Army. David is arrested but, during the night, escapes to Julia’s house to say goodbye and confess that Taggart’s accusations are true. David also admits that he almost asked Spurs to marry him. Before leaving the territory, David and some cohorts plan to rob the bank during the town’s fiesta. They are spotted while breaking into the bank, and one of the gang is killed in the ensuing exchange of gunfire. The others escape in a panic, and their horses trample Father Gabriel. After tracking the outlaws to their hiding place, the sheriff asks Julia to talk to David before the posse turns into a lynch mob. Spurs, too, goes to David, sneaking into the abandoned building where he is hiding alone, after his cohorts have surrendered. Although Spurs fears the wrath of the mob and urges him not to give himself up, David takes Julia’s advice and surrenders. When he impulsively tries to run away, however, he is shot and killed. Days later, Julia prepares to leave town, knowing that her neighbors blame her for David’s crimes and resent her boldness for entering a “man’s” occupation. As she loads her buckboard, a crowd gathers outside to urge her to leave. Before she departs, Rork arrives and, by shaming the ringleader of the hate-filled crowd, convinces the rest to accept Julia. After pronouncing Julia the best doctor in Santa Fe and his future wife, Rork drives her to his home.