William Fielding, a young widower, is living in Shanghai with his little boy, David. A young Chinese woman looks after the child, and Foo Chang, a trader, lusts after her. Because he believes she is David's mother, he kills Fielding. Fielding's faithful secretary, Li Clung, takes the boy to San Francisco to be raised by his grandfather. As an adult, David (also played by Gilbert) fights against opium trafficking with Li Clung's help.
