Dragon Fist (1979)

Since bursting onto the martial arts film scene in 1973, Jackie Chan has become one of the world's most popular stars. His movies -- which he acts in, performs his own stunts for and often directs -- have earned millions at the box office.
In DRAGON FIST, he plays Juan, a vengeful young kung fu fighter, who tracks down the man who killed his master. Joining Juan on his journey are the master's wife and beautiful daughter. However, once they find the culprit in his remote village, they discover he has suffered so much guilt over the deed that he's mutilated himself. As a result, the master's widow chooses to forgive him.
But the story doesn't end here, because Wei, a vicious war lord, learns of Juan's incredible martial arts skills and tries to convince the young fighter to join him. And it becomes nearly impossible for Juan to refuse after the widow comes down with an illness that only the Wei family knows how to cure.
Now the kung fu expert must decide whether to join the evil war lord so the woman can get well again.