'Sons of the Pioneers' is not actually about the Sons of the Pioneers, more's the pity; the title is more in the nature of a hat-tip with a very loose connection to the plot: Roy is the son and grandson of famous lawmen after which his hometown was named. The Pioneers are on hand, of course, but if you blink in the wrong places you might have a hard time spotting them - it's Roy's movie all the way.
When lady rancher Louise Harper (Maris Wrixon) demands a new sheriff to replace George 'Gabby Hayes,' who hasn't been able to catch the night-riders burning down local ranchers' barns, Gabby gets the inspiration to bring Roy out from the East where he grew up to follow in his ancestors' footsteps. Roy decides to play on the townspeople's perception of him as a cowardly tenderfoot in order to lull the villains' suspicions while he investigates surreptitiously and "scientifically." He's helped and hindered by Gabby and his deputy Pat Brady, who provide loads of comic relief, notably Gabby's juggling bottles of nitroglycerin and a very funny scene in which they believe they've seen a ghost. Bradley Page is the villain who spends most of his time chewing out henchmen Hal Taliaferro, Tom London and Jack O'Shea for muffing repeated attempts to put Roy out of commission. Bob Nolan, the only Pioneer besides Brady to get some decent screen time, has few lines but is on hand in the understated part of Louise's faithful ranch foreman. Maris Wrixon, whose character doesn't really fit into the traditional love-interest pattern, makes a lovely and spirited heroine and you wish she actually had more scenes.
Maybe she did. Unfortunately this is one of the handful of Roy's movies whose original full-length print has gone missing. At least two songs were cut (you can easily spot where the number "Come And Get It" was excised from the opening scene) and probably some more footage - I once saw the original trailer which included a scene of Roy making a speech during the sheriff's election campaign. The remaining songs, of course, are naturally excellent. It's a fun film with an interesting premise and characters, some good action scenes and plenty of comedy.