Teenaged fugitive William Bonney is given a second chance when a kindhearted ranch owner, John Tunstall, offers him a job. Within days, Tunstall becomes a close friend and something of a father figure to young Bonney. But when his new employer is killed in cold blood, Bonney reverts to his criminal ways and vows to seek vengeance. Enraged and once again alone, Bonney faces off with the men who gunned down Tunstall and the bullets begin to fly. Years later, gunfighter-turned-newspaperman Bat Masterson enters the campaign headquarters of congressional candidate Robert Widenmann, who also worked for Tunstall, to find out how a young William Bonney was transformed into the notorious Billy the Kid.

In 1880, Bat Masterson's old friend, Ben Thompson, asks him to help save his brother from the gallows. Ben's brother, Billy, has evidently shot off a man's thumb in a gunfight and is wounded himself. While Billy claims self-defense, an overzealous sheriff is eager to see him hang. Though he is no longer a lawman, and he lacks any kind of legal authority, Bat agrees to travel to Nebraska to talk to the sheriff. When his common-sense appeal fails to impress the sheriff, Bat hatches an elaborate plan to help Billy escape, which only succeeds when Buffalo Bill shows up to lend a hand. Years later, when Bat's editor balks at printing the tale, Bat tries to explain the difficulties of dispensing justice in the Old West.