Trigger, Jr. (1950)

“All-Star Big Top Thrills... as you have never seen them before!”

Evil Grant Withers lets a killer horse loose to ruin valuable horses on nearby ranches. He hopes to shake down the ranchers for his "protection". Roy tracks down the bad guys, but is suddenly trapped by them. Peter Miles, a boy terrified of horses, overcomes his fear and rides for help to save the day.