This B western starring Tom Keene was a bit of the average of the Monogram Studio product of its day. The story was not a bad one and this could have been something from Republic or a major studio B picture unit.
Keene and sidekick Frank Yaconelli are a pair of 'government men' who get themselves involved in a range war. This one actually has a bit of truth to it. I. Stanford Jolley owns a rail spur line where the local ranchers ship their goods. He decides to squeeze the ranchers by charging exorbitant rates for shipping. Jolley is in partnership with another rancher Hal Price whose property sits across the only trail out of the valley everybody lives in. He extorts his neighbors in collusion with Jolley.
Of course Keene's interest isn't entirely benevolent. Incognito he's gone to work for rancher Steve Clark and he's taken an interest in the older of his two daughters, Hope Blackwood. The younger has the delightful movie star name of Sugar Dawn and she's kind of a Shirley Temple as tomboy cowgirl.
Yaconelli had some really funny scenes as a sidekick. He's not so good with a gun, but he's devastating with a sling-shot. You've got to see him at work in the final shootout with the bad guys.
Though it's got typical Monogram production values, I give the creators of Arizona Round-Up an A for effort. Railroads and their shipping practices was a very big issue back in those western days and led to a lot of the radical politics of the latter 19th century. If done at a major studio, Arizona Round-Up might have been a classic.
