This is one of many (comedy) Westerns directed by Burt Kennedy; it was written by Ronald M. Cohen and Dennis Shryack. Robert Mitchum stars as Marshal James Flagg (about whom there's a ballad that plays throughout the film, in the background), an aging lawman whose skills and service helped tame the wild west such that Mayor Randolph Wilker (Martin Balsam) and the residents of his town named Progress have forgotten what it was like in the "old days" when bandits robbed trains. Buddy Hackett appears briefly (uncredited) as a townsman.
When Flagg hears from an old hermit friend of his named Grundy (Douglas Fowley) a description that makes him believe that train robber Big John McKay is in the area, he warns the mayor saying that he needs to organize a posse of men. But the mayor is up for reelection soon and he certainly doesn't want any furor to spoil things for him, so he gives Flagg a gold watch and retires him, leaving the deputy marshal he can better control, a big soft lug named Howard Boyle (Dick Peabody), in charge.
But Flagg decides to follow-up on what Grundy had told him, and finds the outlaws camp near the river. He rousts their horses and sneaks up on McKay (George Kennedy). However, Deuce (John Davis Chandler) gets the drop on him and gang leader Waco (David Carradine) laughs at the too old coots. McKay, it seems, is along for the ride and NOT in charge. In fact, he too is aged and not respected like he once was. He stops Deuce from killing Flagg so Waco leaves McKay in charge of taking care of the lawman. Flagg and McKay brawl, which exhausts both of them and Grundy has to help them back to town, where the now former lawman interrupts the amorous advances of his mayor with another man's wife, Tina Louise as Mrs. Flannagan. Of course, the mayor doesn't take Flagg's warnings seriously this time either, so the lawman returns to the boarding house where he lives; the proprietor Mary (Lois Nettleton) and he are somewhat romantically engaged.
Later in town, Grundy gets into a scuffle with Deuce over the attractive older saloon owner Polly (Marie Windsor), which leads the outlaw into shooting the hermit in the back. Before Boyle too gets shot, Waco intervenes to keep things quiet before the train arrives the next day. Upon learning of Grundy's murder, McKay decides to work with Flagg to stop Waco's gang from robbing the train. They decide to board it early and keep it from stopping in Progress; their efforts are hindered by an old train conductor (John Carradine) who recognizes outlaw McKay but not Marshal Flagg. So the two are arrested, temporarily, before they escape to take control of the train and run it through town and an automobile parked on the tracks. The outlaws give chase and then, encouraged by the mayor, so do the townsfolk in their back-firing automobiles and horse drawn carriages. It's a sight to see! Eventually, the train comes to a bridge that's out and it crashes down a hillside shortly after Flagg and McKay have jumped clear. There's a climactic shootout in which McKay has a showdown with Waco. Guess who wins? Then the mayor congratulations Flagg, who puts the cuffs back on McKay promising to take him in.
When Flagg hears from an old hermit friend of his named Grundy (Douglas Fowley) a description that makes him believe that train robber Big John McKay is in the area, he warns the mayor saying that he needs to organize a posse of men. But the mayor is up for reelection soon and he certainly doesn't want any furor to spoil things for him, so he gives Flagg a gold watch and retires him, leaving the deputy marshal he can better control, a big soft lug named Howard Boyle (Dick Peabody), in charge.
But Flagg decides to follow-up on what Grundy had told him, and finds the outlaws camp near the river. He rousts their horses and sneaks up on McKay (George Kennedy). However, Deuce (John Davis Chandler) gets the drop on him and gang leader Waco (David Carradine) laughs at the too old coots. McKay, it seems, is along for the ride and NOT in charge. In fact, he too is aged and not respected like he once was. He stops Deuce from killing Flagg so Waco leaves McKay in charge of taking care of the lawman. Flagg and McKay brawl, which exhausts both of them and Grundy has to help them back to town, where the now former lawman interrupts the amorous advances of his mayor with another man's wife, Tina Louise as Mrs. Flannagan. Of course, the mayor doesn't take Flagg's warnings seriously this time either, so the lawman returns to the boarding house where he lives; the proprietor Mary (Lois Nettleton) and he are somewhat romantically engaged.
Later in town, Grundy gets into a scuffle with Deuce over the attractive older saloon owner Polly (Marie Windsor), which leads the outlaw into shooting the hermit in the back. Before Boyle too gets shot, Waco intervenes to keep things quiet before the train arrives the next day. Upon learning of Grundy's murder, McKay decides to work with Flagg to stop Waco's gang from robbing the train. They decide to board it early and keep it from stopping in Progress; their efforts are hindered by an old train conductor (John Carradine) who recognizes outlaw McKay but not Marshal Flagg. So the two are arrested, temporarily, before they escape to take control of the train and run it through town and an automobile parked on the tracks. The outlaws give chase and then, encouraged by the mayor, so do the townsfolk in their back-firing automobiles and horse drawn carriages. It's a sight to see! Eventually, the train comes to a bridge that's out and it crashes down a hillside shortly after Flagg and McKay have jumped clear. There's a climactic shootout in which McKay has a showdown with Waco. Guess who wins? Then the mayor congratulations Flagg, who puts the cuffs back on McKay promising to take him in.