Jiang Hu tells two stories simultaneously . The first is about a gang leader, Mr. Hung (Andy Lau), and the tensions that arise between him and his old friend and second-in-command, Lefty (Jacky Cheung) due to Mr. Hung's wife's recent child birth. Now that Hung is with a child, Lefty feels that Hung should leave the gang business as he is now burdened with family and that will show weakness in character by their own under-bosses. Lefty also believes that it is his own turn to run the business in his own direction.
The second story is about two teenage low ranking gang members named Yik (Shawn Yue) and Turbo (Edison Chen), who are hoping to gain respect and rank in the gangs by performing a hit on a gang leader. The gang leader is not displayed in the movie, and the audience is to expect that Yik and Turbo are planning to murder Mr. Hung. (Wikipedia)