I've often thought that Gary Cooper's career bears some comparison to Johnny Mack Brown. Both did westerns and other kinds of films during the silent era just like this film The Last Outlaw. But Cooper always varied his output whereas Brown when sound came was relegated to B westerns. With some bad career moves Gary Cooper also could have been relegated as such.
The Last Outlaw casts Cooper as a young sheriff determined to break a cattle rustling ring. But the problem is just who is doing the rustling and why. The 'rustlers' have a very good reason for what they're doing and the real villain of the piece Herbert Prior is a big rancher who does some real magic with a running iron.
Cooper's deterred somewhat from duty by falling for Betty Jewell whose brother is suspected of being a rustler. Later on when brother Jack Luden is killed, that also kills for a time any romance. And Cooper was never in the school of a cowboy whose true love was his horse.
Best scenes of the film are Coop with young Billy Butts. They have a kind of Red Ryder/Little Beaver camaraderie.
The Last Outlaw is a good western, but also barely gives you an idea of the charisma and talent of Gary Cooper.