An aging lawman hears that his old nemesis is back in the area and planning a robbery.

Learning that his longtime antagonist, John McKay, is in the town of Progress, middle-aged Marshal Jim Flagg warns Mayor Wilker that robbery is imminent. The mayor, however, concerned with the alarm's effect on his political future, retires the marshal, promoting in his stead the incompetent deputy Boyle. Flagg conducts his own investigation; he locates the gang, but discovers that McKay is just a nominal member of the youthful band. Although Flagg is captured, the sentimental McKay refuses to allow him to be killed. Left alone by the gang, the old associates brawl. When the exhausted pair is transported to Progress by the eccentric hermit Grundy, Mayor Wilker refuses to admit McKay to the jail. Undaunted, Flagg installs the outlaw in a boardinghouse run by his lady friend, the widow Mary. Arriving in Progress, the youthful bandits promptly slay Grundy. Realizing that their object is the train, Flagg alerts the mayor. Assisted by McKay and the townspeople, he routs the gunmen. Filled with gratitude, Wilker offers Flagg his old job, but the gunfighter declines.