Sons of the Saddle.

Jim Brandon, foreman of the Wind River Ranch, owned by Martin Stavnow, is in love with Ronnie, the rancher's daughter, though he is unaware that Harvey, a youthful cowhand, also loves her. Thus, Jim asks the boy, whom he protects like a brother, to speak for him. When he is spurned by Ronnie, Harvey decides to join Red Slade's gang, who are plotting a raid on the Wind River herd. As Jim forcibly attempts to separate him from the gang, Harvey is killed; and through the aid of his horse, Tarzan, Jim foils Slade's attempt to stampede the herd. Slade takes refuge in a wagon where Ronnie is hiding; Jim rescues Ronnie from the wagon just before the runaway team plunges over a cliff with Slade riding to his doom.