Gwandongsalmusa (1983)

Kal Ma-ryong's mother was raped and killed by thugs when he was young, so he grows up learning martial arts. He searches for his mother's killers and takes his revenge on Cheon-su. The man had a wife and boy; Mun Il-pyung, who searches for a master to study with so he can get revenge. Ma-ryong is found bloody and beaten, but once recovered he unknowingly trains Il-pyung. Will Il-pyung find out Ma-ryong killed his father?