Born to Fight (1936)

An honest boxer refuses to throw a fight for a gambler. They get into a fight and the boxer knocks the gambler out. Thinking he's killed him and believing that the police are after him, the horrified boxer runs off and takes to the road, promising never to box again. However, one day he comes upon a small but scrappy young kid who has the potential to be a champion. The former boxer takes the kid under his wing and trains him, but the kid's ensuing success starts to go to his head. Pretty soon he finds himself mixed up with gamblers, too.