Call of the Canyon (1942)

Cattle buyer McCoy has run up gambling debts. When Gene and the other ranchers are ready to sell their cattle, he undercuts his bosses price planning to pocket the profit. The ranchers then try to drive their cattle to another market but McCoy's men set off an explosion and a rancher is killed. Knowing McCoy listens to the horse race results, Gene sets up a phony radio broadcast hoping to trap him.