The movie starts with Sammo and blackie driving around in two cars on the street.
Sammo tosses blackie a golf club and they are facing off. A motorcycle cop shows up and asks blackie if there's a problem. There is no problem.
Then there is a flashback. Blackie (Simon Yam) is the detective supervisor, he has some sort of brain cancer. It is his last day on the job before his retirement. He has like 4 cops working under him. The new detective chief is Donnie Yen. They said he turned a dude into an invalid one time with one punch. Donnie is going to the cop station and he sees blackie and the boys watching a video. The boys leave to go somewhere.. Donnie asks if he should come too.. Blackie says he should stay at the station and its none of his business. Donnie finishes watching the video and realized that Sammo or somebody killed the undercover guy. Blackie had promised the undercover guy that he would be safe.. but Sammo or hat dude bad guy killed the undercover.
The 4 subcops and blackie go to the apartment where hatman is located. They proceed to beat hatman and hatman flees across a cable in attempts to escape. Hatman falls off the roof and cable to his death.
Donnie catches up to the bad cops and gives them shit. He starts beating on them with his martial arts and one of the cops (blackie?) points a gun to Donnies head and Donnie stops beating.
There is an enemy territory downtown. One of the bad guys throws a bottle on the ground. Meek old cop dude tells him to stop it and pick it up. Bad guy refuses. Donnie and Blackie show up. They said after midnight it is the bad guy's territory and they rule. Donnie and Blackie pull out their guns and threaten the bad guys. The guy that threatened meak cop was forced to back up onto the cracked glass. Sammo arrives and taps the railing with a bottle. All the bad guys throw bottles on the ground.. Donnie and Blackie retreat.
Donnie plays video games (CAPCOM SNK King of Fighters?) with the dimwit that he created by punching out a guy into the head. He created a dimwit with one punch. He lets the dimwit win the game with a bet. He feels sorry for the dimwit and always gives him money every weekend. It was actually one of Sammo's real sons that had this cameo as a dimwit.
Sammo is at the hospital. He is sitting down and waiting for something. A little girl comes by and asks if Sammo would like a candy. He said sure.. nice girl. Blackie comes by and pulls the daughter away.. and says.. asshole.. Blackie has brain cancer and will die sometime. Forgot why Sammo was at the hospital..
Sammo is going through a lobby with a big Pink Panther stuffed bear. He is ambused by the cops and fights Donnie with the other cops. A wack of the cops pin down Sammo arrest him and bring him back to the cop station.
Blackie wants to arrest Sammo because he killed the undercover.
But the bad guys intercepted the little dimwit boy who had a camcorder and saw hatman kill undercover with a bullet.
This cop was beating dimwit kid and trashing dimwit kid's room and thought he had taken all the tapes pertaining to the killing of undercover guy. but dimwit kid went to the cop station and gave the evidence tape to one of the cops. Sammo was not ultimately responsible for killing of undercover. It was hatman who had died from the roof.
Sammo was in jail in the cop station. He was speaking with his lawyer and his wife on the phone. He was told that he was cleared of all charges and he was free to go.
One of the cops was outside a subway station watching a soccer game. He was there to buy a gun from a mafia rep. All the soccer players exited into the subway station.. The mafia guy said he was going to get the gun and come back. By the time the cop encountered the locked subway entrance he realized he was setup and got scared. This blondie guy in a white suit starts running.. He really carves up the cop. Donnie realized that shit was going down and he comes to rescue this cop. By that time the white suit killer (Wu Jing) had carved up the cop and gave him his sunshades. Wu Jing uses cop as a shield.. Donnie doesn't realize that the blows were fatal and Donnie refrains from shooting. Wu Jing escapes and Donnie cradles the doomed cop.
A bunch of the cops are in a room reminiscing about their girlfriends, wives, dads, etc. They said they're gonna meet their family and loved ones. One by one the cops are killed off by white suit dude (Wu Jing). You see a girl and a cop talking about horoscope and then the girlfriend leaves. Wu Jing drops by and slices the cop in the throat. Donnie shows up and holds the cops throat.. and tells him to speak slowly and take his time. Other cops die
Cops raid safe house mafia headquarters and seize Sammo's money bag.
Sammo said, return my money and you will be forgiven.
You see blackie walk into the mafia building with the bag of money.
Wu Jing slices him up and blackie crawls to a sofa. Wu Jing plays with him and pokes his arm with the knife.
Sammo hangs up blackie like a chandelier.
Donnie goes to blackie's supervisor the superintendant i guess. the leader of the cop station. Donnie says fuq it and turns in his badge. He gets the bag o cash and goes to save blackie.
Donnie is coming to rescue blackie. Blackie's bag was a decoy it didn't have real cash in it.
Donnie fights Wu Jing. In reality both Jingy and Donnie are experienced martial artists. They improvized and choreographed the fight on the spot in 1 night. Donnie is using a police baton and Wu Jing his signature knife.
Donnie ulitmately killed Wu Jing in revenge for the cop deaths.
Donnie fights Sammo wrestling style. The phone rings Sammo's wife and baby boy are on the phone. She is parked outside she is asking if she should come inside the building. Sammo says no, he has to finish some business and he will be outside soon and stay in the car. Donnie lifts Sammo over his head and Sammo drops onto a glass bar and is impaled and dies.
Flash forward Donnie is at the beach. Someone had adopted a daughter to take care of her. You see a beach ball floating around in the surf and the surviving cops are with Donnie.