A Go-Go Teenager (1966)

Two orphan boys indulge in petty theft after the war. One, Chow, is caught but gets adopted by a policeman. He turns out a solid young citizen. Lee, the boy who escapes, grows up to be a triad. When the two re-meet, Lee is attracted to Chow’s stepsister. Some years later, Chow is now a cop and vows to smash Lee’s gang. After a struggle with his conscience, Lee agrees to help.

Unfortunately the movie A Go-Go Teenager is not yet available on HBO Max.