The credits begin with scenes of two men firing handguns and automatic weapons at a shooting range. There is a clip of one man shown to be a combative rec softball league manager. The other is a chess player who speaks of a former grandmaster going paranoid and crazy. A grainy black and white video of one of the men starts. He says he is David Fisk, Detective 1st Grade of the NYPD for nearly 30 years and he has killed 14 people.
His narration continues saying it all started about four years ago with the case of Charles Randall who murdered his girlfriend's daughter but was acquitted and released. Fisk's partner the chess player gazes at a passing priest and group of choirboys. Fisk takes a handgun from an evidence box and his partner realizes what he is doing and tries to convince him otherwise, telling him he is his role model. The two cops are shown hiding the gun under a sofa cushion and then Randall is shown being taken away in cuffs, "lost his freedom for a crime he didn't commit" says Fisk. The partners are shown sitting in a church and Fisk narrates that he "lost his faith".
A woman is seen leaving the 104 St. Train station and walking to her apartment. She picks up her mail and we see her name "Karen Corelli". She enters and scans her mail. Suddenly a man's arm comes out, clasps her mouth and pulls her offscreen. There is sounds of a struggle and a woman moaning. Then Fisk is seen shirtless on a bed and the woman calls him "Turk", telling him "not bad" but teasing him for how weakly he pulled her hair as she dresses.
Turk/Fisk's narration continues as he says things heated up a couple of weeks ago. The two cops are sitting in a car outside a lively dance club "404" in Harlem, discussing the owner Marcus Smith aka Spider, a man with known criminal activities. They enter the club and talk about how the converted bank is used for money laundering. Turk goes to the men's washroom and is peeing at a urinal when an attractive young woman comes in and starts chatting. She lays down some cocaine and proceeds to snort it, mentioning Spider provided it. She offers some to Turk who then flashes his badge.
A skateboarder is shown forcing a prostitute into a cab. Turk/Fisk's b&w video plays as he states Rambo the pimp was his 10th victim. The skateboarder is shot in the chest and the handgun and small white note with writing on it are tossed on the street.
The police mobilize at the crime scene and the two partners kneel over the body. The card has a short poem justifying the killing. They joke about the dead man's name Bobby Brady and the 1970s TV show The Brady Bunch. Karen is in NYPD uniform and gloves gathering physical evidence as a CSI. She refers to Fisk's partner as "Rooster". The two partners continue to discuss the case back in the office. Turk hints at a lot of sex with "you know who" and a low sperm count. They go to a bar to speak to a Russian woman, one of the dead pimp's hookers. Turk threatens to call Immigration when she doesn't co-operate and Rooster gives her his card. The two discuss the case with their boss, Lt. Hingis. wanting to concentrate on Spider instead. Hingis also mentions they should just let the cocaine blond go without prosecution because she is a lawyer.
The partners are leaving a black car with the cocaine woman from the 404 club. They enter a warehouse and discuss an undercover sting operation she, her name is Jessica, will help them with to arrest Spider in return for clearing her record. She goes next door to Spider's place wearing a hidden mic while the police sit in a large room with electronic surveillance equipment and other police. The partners joke around and listen to the conversation and soon realize Spider is becoming suspicious. The cops rush into Spider's house as he taunts them for a poor effort at entrapment. A large associate of Spider lurks in the background and suddenly a gunfight starts. Jessica is shot and the large man is killed. Spider is handcuffed laying on the floor. Jessica appears to be seriously injured and Turk calls in backup. He goes to Spider and starts kicking him until Rooster stops him. The rest of the police arrive.
Later in the police station a female DA is berating the two for a cluster f*** operation but if they keep their stories straight with IAB they will get off. Spider will nto be charged with any crime. Lt. Hingis also reams them out and tells them they will have to go to psychological counselling. The two are nterviewed by Internal Affairs, they tell basically the same story and the IAB cops agree they did nothing wrong. Then they go through the motions with a police psychologist who gives them small notebooks to record their thoughts.
Turk and Karen are having sex, she is urging him "harder...harder!"
In a park Rooster is in the stands cheering on a police intra-mural softball game. Turk as a player escalates a home plate incident into a full brawl. The b&w video comes on with Fisk/Turk saying "he is a safety valve" as the two IAB cops watch. Back at the park Turk chats with a couple of younger cops after the game and they begin to discuss the Rambo murder. They have a similar case with a dead gun runner named Trager and a similar poem. Rooster arrives and the four say they will work together. The narrator Fisk states the gunrunner was victim #11.
In the office Karen comes to tell to Turk and Rooster she has info from ATF that the Rambo gun was one of six Trager stole in Virginia. Turk leaves and Rooster exaggerates Turk's violence in describing the Spider incident to a very interested Karen.
In court a judge dismisses a rape/assault case against a man, Van Luytens, due to errors in the chain of custody. Turk angrily threatens the smirking Van Luytens as he leaves the courtroom.
A pensive Turk is riding the subway alone while the Fisk narrative draws an analogy between life and baseball's infield fly rule. At the same time Van Luytens opens his door to greet a visitor and is met with bullets to the chest, a gun and note fall to the ground. The next morning the four detectives are at Van Luytens' apartment, Karen is gathering evidence and Rooster teases her about her private life.
Back at the office Lt. Hingis urges Turk and Rooster to solve the case quickly or their pensions may be at risk. Rooster makes an allusion to Ted Williams saving his .406 batting average on the last day of the season. Turk, Rooster, Riley and Perez begin to review the files.
The Turk/Fisk narration describes his first murder and how he idolized "Tom Cowan" his role model and partner. He mentions how lucky they were to have a lawyer as a witness and at the same time as Turk is talking to Jessica and the cops go back to the the 404.
Karen comes to the office and tells Rooster there is something about the gun used in the Charles Randall case and suggests someone talk to him in prison. Turk and Rooster drive up to the prison and have a short, profane and useless interview. Later the cops go to a bar and Turk complains about meeting Karen's needs. He also expresses regret at framing Randall. Rooster tells him it was the "righteous" thing to do.
The four detectives brainstorm back at Van Luytens'. Rooster leads the discussion and three of them realize the killer must be a cop. Turk is angry and denies the possibility.
At home, Karen is dressed up as Turk just finishes his pushups on the kitchen floor. She refuses to go out to dinner and they have a bitter conversation about her promiscuity.
At a gym weight room the four detectives continue to discuss the case. Perez makes a crude humping gesture referring to Karen, Riley mentions they used to date. Turk is getting upset and mentions that a fired Lt. Martin Baum would be a possible suspect. The other three don't see his logic and Turk storms off.
Turk and Rooster come to their office and find Karen going through the case files. Turk angrily lifts her from her chair and holds her in a tight embrace. Rooster excuses himself and Karen apologizes for the other night. They nuzzle.
Perez and Riley are on a stakeout following a man in a tan windbreaker, Perez saying this is all a misdirection by Turk. He also has Turk's pers files and notes Turk is an accurate shot. At the same time Turk enters Karen's apartement and goes to her PC. The windbreaker man enters a building. Turk sees on the computer the police files of the serial killer victims. Riley leaves the car to follow their suspect, who then appears at the car door with a gun pointed at Perez. Riley returns and regains control. The windbreaker man is former Lt. Baum, still bitter at being fired but he provides a passport and papers to prove he was in Brazil recently as an alibi. At a church a priest is telling someone he doesn't recall him, he's had so many altar boys. A shot rings out and the priest falls dead. Fisk video states Father Connell was #13, one to go.
Turk and Rooster arrive at the church and Karen is already there gathering evidence. There is another poem. Turk mentions Father Connell gave him his first communion. Perez and Riley arrive. A little later Perez and Riley discuss cop serial killers with Dr. Prosky. He says he's never seen it but serial killers usually want to get caught in the end. Concurrently, Jessica comes to the ballpark to thank Turk for everything. They chat and Turk says his daughter is 25 and living in California, his wife died when the daughter was very young.
Perez and Riley go to Lt. Hingis with their suspicions about Turk. They have found out that Father Connell was probably a child molester and Turk would have a motive. Hingis tells them they need more evidence. Hingis then talks to Turk alone and hints that he is a suspect. Hingis also meets Rooster in a diner to discuss Turk, Rooster is adamant he knows Turk is not the killer and is the most people-caring cop.
Rooster startles Karen in a file room. He bluntly asks her to have sex saying Turk wanted them to. Karen seems bemused then Rooster changes the subject and asks for her to provide some information "discreetly".
Rooster calls Perez and asks to meet at a bar to discuss Turk. He arrives to the meeting with Sheryl, the mother of Randall's 10 year old victim. A shaky alcoholic, she admits she provided the alibi that allowed Randall off. Rooster sends her off then admits to Perez and Riley that they framed Randall. Rooster says he will help Perez and Riley but whatever else Randall's conviction must not be overturned.
Rooster and Turk meet with Dr. Prosky again. Turk rides a subway home staring down punks and recalls earlier in the day Lt. Hingis gave him a written notice putting him on restricted duties for not being co-operative with the shrink. The next morning Turk is furious at Perez and Hingis, Rooster tries to calm him down. In the evening, Karen leaves a voicemail for Turk explaining her night class ran late, apologizes then enters a car to go on a date with Perez. Turk has Perez' per file and makes a phone call.
Turk and Rooster meet for dinner at Salerno's. Turk says he has found out that Perez has exaggerated his education and was thrown out of another precinct. The two overhear a large Russian man bragging about his BMW 7-series at the bar, Turk identifies him as Yevgeny Mugalat, an enforcer for the Gambinos.
Rooster offers that he has been using the Prosky notebook and finds it very useful, but private. The Fisk video narrates that routine police work made him sick, at the same time someone approached Mugalat at his car. The Russian greets the person "Detective.." and is promptly shot. The Fisk voiceover continues, someone shoots at Perez from a distance. The Fisk video says he wasn't expecting a retirement party.
Karen is walking home at night. She notices a car following her and calls someone, leaves a voicemail to come as soon as they can. She finds a small note on her countertop. Someone is buzzing at the door, Karen points her gun, the door opens, it is Turk. He grabs the gun from her and demands to know what is going on, what is she hiding? A tense conversation, Turk finally wants to know what info Perez has on him.
The next day Riley and Perez, head out of the office. They meet Rooster at the hospital to see Mugalat, now semi-conscious. The doctor calls him "a tank" having taken six bullets out. Mugalat doesn't respond to questions and Riley calls in 24 hr guard for him.
At the 404 Spider calls Turk offering some information on the serial killer guns. They agree to meet at the club on Friday. Riley and Perez are with Spider and say the cops will leave him and the club alone if they can get Turk.
Someone walks toward a sleeping Mugalat going for the IV when suddenly a young uniform cop calls out "Evening Detective" and offers a coffee. The Fisk voiceover says he had to change the rules when he heard the Russian didn't die. Turk writes a little note. At the office Perez slaps Karen on the butt as Turk watches in dismay. Fisk says he went for the "unforgiveable".
At Karen's apartment she goes to her bathroom wearing a robe. Someone attacks her, there is sounds of struggle. She rises slowly, bloody and wrapped in the shower curtain. Someone leaves and Karen calls Lt. Hingis. She is upset Hingis doesn't take it seriously and angrily leaves with her gun.
Turk jogs through the streets in his sweats. Karen checks the reservation book at Salerno's and sees "Fisk 2" written. She tries to contact Perez and Riley. Turk arrives at the 404. Perez, Riley and Rooster are at the surveillance spot observing Spider and Turk's conversation. Turk talks about writing a poem and Perez and Riley rush over guns drawn. Turk laughs and Rooster reads the note, Turk had predicted the entrapment. Perez pats down Turk looking for another weapon then takes a swipe at his head. Riley and Perez leave but say they'll still be after him. Rooster takes Turk to a sideroom and goes off to see Spider. Karen shows a picture to Mugalat who nods in agreement. Turk finds a small notebook on the sofa and begins to read it. Rooster shoots Spider in the back of the head. A speechless Turk hears the shot and enters the room, Rooster points his gun and tells Turk to sit down and read the book, "for the record" indicating a surveillance camera. Turk begins to read "I am David Fisk, Detective 1st Grade of the NYPD for nearly 30 years..." It is the Fisk b&w video from the start.
Rooster Fisk recalls the recent murders as Turk reads. Rooster breaks the camera and explains Turk was a great cop but when he broke the law in the Randall case he let Rooster down, he lost his faith. Rooster leaves suddenly and Turk follows a few seconds later. He follows Rooster through the warehouse and confronts him again in a wide open floor. An angry Karen appears behind Turk with a gun. Turk gets the gun away from a crying Karen and chases Rooster again. In another room Rooster stops and challenges Turk to follow procedure, a "1010". He takes potshots at Turk trying to get him to return fire. Rooster aims directly at Turk but Turk Cowan is faster and shoots Fisk twice. Turk calls in an "Officer down" emergency but a dying Rooster asks him to cancel it.
The IAB officers and Turk finish watching the b&w video. They agree to close the case. At a girl's softball game Turk looks on sadly as Karen looks on sympathetically. Turk goes to the girls and leads them in a cheer. End credits.