Wayne is Rocklin, a stranger who hits town in a stagecoach with a letter from a ranch owner promising him work. But the ranch owner is dead, and the relatives that are taking over the outfit are the naïve young Clara Cardell and her spiteful scheming aunt, Elisabeth Martin. The old woman will have nothing to do with Rocklin -- and he has no fondness for her -- so he takes on a job at another ranch, owned by businessman Harolday but run by his stepdaughter Arly (Ella Raines) who has taken quite the liking to Rocklin. Clara seeks Rocklin's help when it seems her aunt and her lawyer, Robert Garvey (Ward Bond) are conspiring to take the ranch away. Rocklin and his friend Dave ("Gabby" Hayes) have to help Clara and figure out who killed the ranch owner before she loses the ranch and he loses even more.
Since he's not an icon by this point, Wayne actually has a little more freedom with his character than he will have in some later roles. Arly's pinpoint pistol shooting unnerves Rocklin enough to admit he needed the drink he took afterwards, something the later Wayne wouldn't do. Rocklin's charge-ahead tendencies muddy the waters as often as not, and his own stubbornness brings about more trouble than needed to solve everything. He unfortunately never worked with Ella Raines again, robbing audiences of more chances to see the pair work together. The couple provides plenty of spark, but it doesn't all come from the Duke, as Raines is probably one of the best non-Maureen O'Hara leading ladies of his career.
It may have been thrown together for as little as possible as quick as possible, but Tall in the Saddle turned out to be a little gem and probably a good reason Wayne's career kept heading upward.
So there's not much to distinguish the John Wayne of The Train Robbers from the John Wayne of Cahill, U.S. Marshall, or really even from the John Wayne of True Grit or Rooster Cogburn. In Robbers, he's Lane, a kind of wandering adventurer who's agreed to help a woman, Mrs. Lowe, (Ann-Margret) recover the railroad gold her late husband stole and hid. Recovery of the gold will allow her to claim the reward money and put right her husband's reputation for the sake of her young son.
Lane's helped by two old comrades, Jesse (Ben Johnson) and Grady (Rod Taylor), and three younger men who will, by the time the movie's over, get a good schoolin' in what it means to be a man according to the Duke's way of thinking. The party will travel to Mexico, pursued both by the thieves who helped Mrs. Lowe's husband rob the train and by a mysterious loner played by Ricardo Montalban.
There's a little suspense in wondering how the group will survive or if all of them will and how things will all end up, but not much. Audiences didn't pay money to watch John Wayne lose. The movie wisely eschews the idea of a Duke-Ann-Margret romance, with Lane making the obvious remark at one point: "I've got a saddle that's older than you."
Wayne knew his audience and made the movies he wanted to make and the ones they wanted to see, but in so doing he rarely stretched himself as he did earlier in his career. Even though The Alamo was a big-budget flop, it was at least something that came from a creative vision, which Robbers lacks. The disappointment it brings is not that it's a standard John Wayne picture. It's that with all of the creative control at Wayne's command, it should have been that plus something more.