When the Clantons steal his family's cattle and kill his brother, Wyatt Earp signs on as sheriff of Tombstone and vows to bring them in.

While driving their cattle through Arizona on the way to California, the Earp brothers, Wyatt, Morgan, Virgil and James, encounter Old Man Clanton and his son Ike, who offer to buy the cattle from them. Wyatt turns down their offer, and later that night, the three older brothers ride into the nearby town of Tombstone, leaving James behind to guard the cattle. After Wyatt subdues the drunken Indian Charlie, he is offered the marshal's job, but declines. When the brothers return to their camp, however, they discover that the cattle have been rustled, and James has been killed. Wyatt then pursues the marshal's job, determined to avenge his brother's death. Later, in the saloon, Wyatt encounters gambler Doc Holliday, who tries to provoke a confrontation with the new marshal. When he learns that he is surrounded by Wyatt's brothers, however, Doc relents and buys Wyatt a drink. Wyatt discovers that Doc is well-educated and when his recitation of Hamlet's soliloquy is interrupted by a fierce fit of coughing, also deduces that he has consumption. One morning, the stagecoach delivers a well-dressed woman named Clementine Carter, Doc's former fiancée, to town. Her sudden appearance stuns Doc, who advises her to return to Boston. When she begs him to accompany her, he angrily informs her that if she does not go, he will leave town himself. Later, when a drunken Doc goes looking for a fight, Wyatt knocks him unconscious and takes him to his room. The following day, saloon singer Chihuahua, Doc's girl friend, tells the disappointed Clementine about her relationship with Doc. While waiting to pay her hotel bill, Clementine meets Wyatt, who is somewhat enamored of her. Together they attend a dance to raise money to build a church in Tombstone. Afterward, at a dinner at the hotel, Doc comes upon Wyatt and Clementine. Furious that she is still in town, Doc leaves the next day on the afternoon stage to Tucson. This angers Chihuahua, who had hoped Doc would take her to Mexico and marry her, and she storms into Clementine's hotel room to help her pack. There Wyatt notices that she is wearing a necklace that James had bought to give to his girl friend. Chihuahua claims that Doc gave it to her, and Wyatt takes off in pursuit of him. After Doc returns with Wyatt, however, he demands to know who really gave her the necklace. At first Chihuahua sticks to her story, but when she learns that the necklace was stolen by the man who killed Wyatt's brother, she admits that it was a gift from Billy Clanton. Billy, who is waiting outside Chihuahua's room, then shoots her. While Virgil chases Billy, Doc reluctantly agrees to operate on Chihuahua with the help of Clementine, who is a nurse. Meanwhile, Virgil chases Billy to the Clanton ranch and is killed by Clanton after Billy dies of gunshot wounds. The Clantons ride into town and, after dropping Virgil's body at Wyatt's feet, announce that they will be waiting for the Earps at the O.K. Corral. That night, Doc reports that Chihuahua has died, despite his surgical efforts, and he joins the Earps in their fight against the Clantons. The gunfight begins at sunup and by the end, all the Clantons, except the father, are dead, as is Doc. Rather than kill Clanton, Wyatt turns him loose to wander and suffer from the deaths of his sons. Before he can get far, however, Morgan kills him. Later, Wyatt and Morgan leave town. Clementine says goodbye to Wyatt and, explaining that she intends to remain in Tombstone, asks him to stop by if he is ever in the area again.