Eagle Clan actively fought the Mongols, who was that the time occupied the land. When the story began, Fu Chung-yuan had just been chosen as the new chief of Eagle Clan by the late chief, his god-father. A woman in mourning clothes came, said that Fu Chung-yuan had killed her husband because her husband had knew a big secret: Fu Chung-yuan was a Mongol by birth. Fu Chung-yuan went away to find his parents, he wanted to ask them; but when he arrived, the parents had been murdered and again he was accused as the murderer.
It ended more or less like in the book, that our hero couldn't choose which land and nation he had to defend.
I have seen the 1997 TVB version which told the story in no flashback and that made the mystery have no surprise. In this 1982 movie version, the mystery did work, and we wanted to know who had framed Fu Chung-yuan.