During the American Civil War, teen-aged Wyatt Earp lives on his family farm in Pella, Iowa, while his older brothers Virgil and James serve with the Union Army. Wyatt attempts to run away, intending to lie about his age and join the war, but his father catches him. His brothers return home at the war's end, with James gravely wounded, and the family moves west. Wyatt sees a man killed during a gunfight, and vomits at the sight.Years later, Wyatt works out west as a wagon driver, also serving as a referee for fights, and finds himself at odds with a bully. Wyatt and the bully come to the point of fighting, with the bully intending to shoot him, but Wyatt disarms and defeats him, taking his gun.Returning home to Missouri, Wyatt marries his childhood sweetheart, Urilla Sutherland. They move into their own house, and he begins working as a policeman. Months later, his pregnant wife dies from typhoid fever. After staying by her side through the illness, Wyatt becomes deeply depressed. Burning their home and possessions, he begins drinking and drifts from town to town, landing in Pine Bluff, Arkansas. He robs a man and steals his horse, but is captured. With Wyatt facing certain hanging, his father bails him out of jail, telling him to never return to Arkansas.Working as a buffalo hunter, Wyatt befriends Bat Masterson and his brother Ed Masterson. Years pass, and Wyatt becomes a deputy marshal in Wichita, Kansas, building a reputation as a good lawman. He is recruited to work as a deputy in Dodge City, with a lower salary but earning extra money for every arrest. In Dodge City, Wyatt kills his first man, witnessed by actress Josie Marcus. Wyatt becomes romantically involved with a prostitute, Mattie Blaylock, and the Mastersons join him as deputies. Wyatt believes Ed is too passive, but the Dodge City council fires Wyatt for his excessive force, appointing Ed to take his place. Wyatt begins working for the railroad, capturing outlaws.Pursuing outlaw Dave Rudabaugh, Wyatt is introduced to gunman and gambler Doc Holliday in Fort Griffin, Texas, and the two become friends. Holliday assists Earp in locating Rudabaugh, whom he dislikes tremendously. Wyatt receives word that Ed has been killed, having shot and killed both his assailants before dying in the street. Wyatt returns to Dodge City to help bring law and order, before moving his family to Tombstone, Arizona, despite the wives' and Mattie's protests. Wyatt immediately finds himself at odds with the outlaw Cowboy gang. He becomes romantically involved with Josie Marcus, angering her boyfriend Sheriff Behan and stressing his relationship with Mattie, and becomes the subject of rumor about town.Wyatt and his brothers Morgan and Virgil arrest several Cowboys, and Virgil takes over as marshal following the murder of Fred White. Tension builds between the brothers and the gang as Wyatt breaks up several altercations involving the Cowboys, particularly Ike Clanton, and Holliday swears his loyalty to Wyatt, whom he considers his only real friend. The Gunfight at the O.K. Corral makes the brothers very unpopular in town. Virgil is ambushed and wounded, and Morgan is killed. In the Vendetta Ride, Wyatt and his friends take revenge against the remaining Cowboys.Many years later, Wyatt and Josie mine for gold in Alaska. A young man on the same boat recognizes Wyatt, and recounts a story in which Wyatt had saved the boy's uncle, "Tommy Behind-The-Deuce". Wyatt says to Josie, "Some people say it didn't happen that way", to which she responds, "Never mind them, Wyatt. It happened that way."An epilogue states that Holliday died six years later in a hospital in Glenwood Springs, Colorado. Members of the Clanton gang continued to die mysteriously for years after Morgan's murder. Josie and Wyatt's marriage lasted 47 years until Wyatt died at age 80 in Los Angeles.