Duel of Fists

Hong Kong's Fan Ko, an engineering architect in Hong Kong who is also highly skilled in martial arts, is called to the bedside of his dying father, who reveals that he long ago had an affair with a woman in Thailand, who bore him a son. He begs Fan Ko to go to Thailand and find the young man, and shows him an old photo, taken when the brother was perhaps 10 years old. But even then, the fierce-looking boy was training in the Thai martial art, Muay Thai, and sported a tattoo on his left arm.