Vice Squad 633(1979)

Original title: Liu san san

Vice Squad 633 sends crack narcotic fighters Wong and Miss Chow to the slums to flush out the traffickers. They catch Spareribs, a minibus driver who has become an addict because he foolishly believed in a quack doctor. Wong and Chow decide to give Spareribs another chance and he offers to be an informer. The Wong-Chow team makes a number of arrests, thanks to Spareribs. Lam Kee, the drug ring's boss, fails in buying Wong over. He decides on a diabolic plan to get rid of Wong...