Wildfire.

Fanning has his men rustle horses and then blame it on a wild horse named Wildfire. Happy and Alkali arrive and immediately get into trouble with Fanning and his men. When Alkali is shot, Happy catches the outlaws but the Judge not only releases them, he discharges the Sheriff and tries to arrest Happy for rustling. Happy escapes and he and the Sheriff then set out to prove who the real rustlers are.