Bat Masterson cleans up Liberal, Kansas.

Western lawman Bat Masterson sets out to prove a man standing trial for murder is innocent.

Fleeing to Dodge City after killing a man in self defence Masterson finds his brother Ed (Harry Lauter) running for sheriff of the town. When Ed is killed by hired guns of the corrupt incumbent Bat is determined to settle the score with violence but he is convinced by the townspeople that the best way to avenge his brother's death is by taking Ed's place on the ballot. Bat agrees and wins the election but his new role on the right side of the law will lead him to unexpected confrontations as he finds himself torn between his loyalties to his friends and his duties as sheriff.

Pat Garrett arrives in Abilene where he catches five of Butch Cassidy's gang. He calls in Wyatt Earp and Bat Masterson and they learn there is a half million dollar shipment of money arriving by train and Cassidy is amassing enough men to take it.

Bat Masterson, who after failing to secure a job as a newspaper reporter becomes marshal of Dodge City. Preferring socializing to peacekeeping, Masterson falls in love with Dora Hand, the obligatory golden-hearted chorus girl whose concern for the welfare of her fellow citizens at time reaches Madonna-like dimensions. When Dora is shot down cattle baron King Kennedy, Masterson begins taking his job seriously. After taking care of Kennedy, Masterson determines to enshrine the memory of Dora, whose efforts to clean up Dodge City were largely ignored by the "decent" townsfolk.