One of the more enjoyable entrées in the Three Mesquiteers series is Red River Range which finds the boys working as government agents to stop some cattle rustling.
Unbeknownst to John Wayne, Ray Corrigan, and Max Terhune the meatpacking industry has hired its own agent, Kirby Grant, to get a line on the rustling. That in itself was an interesting aspect of this film, the inflation of meat prices as a result of cattle rustling. One never does think of the economic hurt, those rustlers cause.
Kirby's cover is blown before he can infiltrate and folks in the Red River country already know the Mesquiteers are coming. So Wayne and Grant switch places and Wayne poses as an escaped killer.
The focus of the investigation is a dude ranch where some mighty strange goings on are occurring. Can't reveal what the scheme, but I assure viewers it's a lulu.
A bit more comedy than usual in this film in the person of old vaudevillian Polly Moran, an amazonian tourist at the dude ranch with eyes on the Duke. Good thing the investigation was over as soon as it was because who knows what John Wayne might have had to do to keep his cover.