Compared to most of the cowboy series films of the era, the Hopalong Cassidy movies are among the very best. He was no singing cowboy and the quality of the films are a tad better than the films of his contemporaries. Take "Hills of Old Wyoming" for example. While B westerns usually ran from 55-65 minutes and seem hurried, this one is 78 minutes and seems less slapped together than the others. This means the acting is better, the sets better and the story a bit more interesting.
For the first 15 minutes, Windy (George Hayes) and Lucky (Russell Hayden) were tracking cattle thieves who were stealing from not just their Bar 3 Ranch but from their neighbors as well. The trail led to the nearby Indian reservation and a nasty agent, Chief Deputy Andrews (Morris Ankrum). But his boss was pretty blind to all this and actually managed to often HELP Andrews in his evil endeavors. So, it's up to Hoppy to come along and piece the mystery together. And, working with the Indians themselves, he finds the man who shoots bullets with a strange notch.
I wouldn't call this brilliant compared to some of the A-pictures but for the series pictures, it's engaging and very well done. It also doesn't insult your intelligence or only appeal to the kids--a weakness with some of the other cowboys' pictures.