Karate 4 (1978)

The complicated story involves the military conquest of a peaceful island-nation by an evil despot and his sorcerer ally. His victory leaves the island's three heroic protectors dead, but, their young children are hidden away to grow to adulthood with different identities, unaware of their heritage, in hope that, in time, they might challenge and defeat the evil ruler. The charming Polly Kuan stars as one of these children who has been adopted by the conquerer himself, initially as an insult to the defeated hero, later as his protégé.