Martinez investigates a baby that was killed in a car from an apparent drive-by shooting. Meanwhile, Lois Snyder contacts Sipowicz for help because a policeman that she was entertaining died in a compromising position and he moves the body to a less conspicuous location. Lesniak's ex-boyfriend, Officer Abruzzo, keeps showing up at the precinct and harassing her, while at the same time, Lesniak locks horns with the officious Vince Gotelli over his working skills and his racy items he keeps. Kelly's future with the department is decided when Internal Affairs comes to the precinct to re-investigate some of his old cases and the result is Haverill transferring Kelly to borough dispatch duty. But Kelly decides to quit the force and after saying goodbye to Sipowitz, he throws in his badge for good.

Simone and Sipowicz investigate the brutal murder of the teenage daughter of a woman whose ex-husband has made threats against her. Meanwhile, Lesniak and Martinez's latest case involves them trying to nab a con artist who sells a black box to homely women, promising them beautiful skin. The new zone commander, Captain Clifford Bass, checks in and lets Fancy know his overtime policy, which doesn't sit well with Sipowicz when it compounds their investigation. Elsewhere, while Simone's romance with Benita becomes more serious, he also deals with a childhood friend, named Ray, who is now involved with a nightclub that is frequented by wise guys and other criminals.

Meadavoy and Lesniak pair up to identify who's launched a series of vicious attacks on a man. Meanwhile, Simone tries to locate a possible suspect in a series of rapes. Russell tries to maintain her sobriety and it's strongly tested when her parents domestic problems get out of hand. Also, Martinez finally gets out of the hospital and returns to duty. But in a final surprising twist, Lesniak tells Martinez that she likes him as friend only... because she happens to be gay.

Sipowicz has race relation problems with the organizer of a local basketball game, held in the memory of a young boy, which erupted into violence by the gang members on the opposing sides which left two dead and seven wounded, and was witnessed by a reporter. Fancy has problems when Sipowicz racist colors come to light and has him removed from the case, much to his anger.

Simone and Sipowicz look into the death of a young woman whose body is found burned beyond recognition, except for a tattoo on her back. Detective Vince Gotelli arrives from another precinct to assist Simone and Sipowicz with their case and puts his two cents in, much to Sipowicz's delight and one of the victim's roommates becomes the prime suspect. Meanwhile, Medavoy pulls double shifts for himself (to get away from problems at home) and is assigned to watch an informant who has a penchant for playing poker with his friends.

Just days after Sylvia gives birth to a baby boy (Theo), Sipowicz suffers an emotional setback when Andy Jr. is found murdered in the line of duty. Sipowicz wants Simone to lead the case of his son's killer and also wants the opportunity for restitution. With Russell in tow, Simone tries to balance his desire for revenge, as well as his quest for justice to catch the killers. While Sipowicz breaks the news of his son's death to his first wife, Katie, he begins to show signs of an emotional breakdown. In the midst of all this turmoil, Donna makes her decision when she quits her job as administrative assistant to the precinct and moves to California, leaving New York for good.

Sylvia confronts Sipowicz about her suspicions that he is going to late-night bars and drinking again, and the effect is everywhere. Lt. Fancy is forced to sent him home after Sipowicz walks in one morning drunk. Sipowicz even fights with some street punks, gets beaten up, and Simone offers to look for the men that beat Sipowicz up. Meanwhile, a new administrative assistant, named Lucy, arrives as Donna's replacement. Also, Russell investigates a young woman, named Angela, who claims to have been stabbed by her jealous boyfriend. Simone, following a lead from a streetwalker named Deena, finally tracks down and confronts the two thugs who murdered Andy Jr. and guns them both down in a hail of bullets.

Medavoy starts a bet with Sipowicz to see who can lose the most weight in a single month. Afterwards, Sipowicz and Simone help out Detective Stuart Morrissey on his investigation in the case of a missing baby. Meanwhile, Martinez campaigns to become the elected delegate for the squad and his opponent, Detective Vince Gotelli, is determined to win the seat himself. Also, Simone makes a deal with Henry to let him share ownership of the building.

An ex-con that Sipowicz put away a year ago approaches him and tells him about a prisoner who's been serving time for a crime he didn't commit and he and Simone decide to reopen the case. Meanwhile, Martinez wins the election by just three votes, much to Gotelli's chagrin. Simone comes across Detective Nick Savino who helps him with the investigation of the murder in his building and Savino suspects Henry has something to do with it. Fancy gets a cavity filling which makes him more edgy than usual and Medavoy loses one pound more than Sipowicz. Also, Russell still has not come to any conclusion about her relationship with Simone.

Fancy and his wife are pulled over and harassed by a racist police officer for a burned out taillight, and he and the precinct commander, Captain Bass, don't see eye to eye on the procedures followed during the stop. Meanwhile, Sipowicz has some unresolved issues to work out Andy Jr.'s death when he begins having a string of dreams involving his late son. At the same time, Sipowicz works with Simone on a rare night duty and gets a case involving trying to find the perpetrators of a bar robbery, while Simone locks horns with the conniving Detective Eddie Hazell who is seeking to derail Simone's investigation to take the credit for nabbing the robbers all by himself. Also, Medavoy, Martinez and Russell work together on a sting operation to catch two female con artist investors defrauding old and crippled women.

Simone and Sipowicz get another case involving the shooting of a rap artist who refuses to cooperate with them in the identification of his assailant. Meanwhile, Abby tells Medavoy that she and Kathy are trying to start a family and asks him to donate his sperm to her so Abby will get pregnant. Officer Szymanski, the racist cop who pulled over Fancy, tells him that he thinks Fancy was one of the ones responsible for his being set-up and caught in the alleged theft of a drug dealer's money. Also, Simone is approached and propositioned by FBI agents to help them with their ongoing investigation into the affairs of mobster Joey Salvo. Elsewhere, the night shift detective, Vince Gotelli, tells Simone and Sipowicz about a heart medical condition of his.

Five Ecuadorians are found murdered at a small nightclub in an apparent robbery gone bad. Sipowicz, Simone, and Martinez work on the case where a tip from a waiter at the club leads them to try to find the two killers responsible. Meanwhile, Simone begins his undercover work for the FBI when he secretly meets with Joey Salvo who wants Simone to run a license plate number for him. Also, Russell and Medavoy are looking into a suspect in a spouse abuse case where Medavoy's commitment to Abby and Kathy hampers the investigation due to Medavoy's emotional attitude. Also, Medavoy discovers that Detective Gotelli is stealing money out of his locker in the light of his medical condition.

An inebriated Vince Gotelli is arrested after "hijacking" a city bus and having it wrecked. Fancy meets with the bus driver's boss to work out an arrangement about their investigation and suggests that Gotelli take some medical treatment. But it takes a forced intervention by Martinez, Medavoy, and Russell to convince Gotelli to get medical and psychiatric help in which Gotelli decides to throw in his badge for good. Meanwhile, Simone's continuing help with the FBI makes his life miserable when the men from Internal Affairs investigate him for the government license plate number on Salvo's car that he ran and is frustrated when he cannot tell them, not even Sipowicz, about what he's doing. Elsewhere, Sipowicz and Simone investigate the beating and murder of a woman in her apartment and deal with the emotionally sensate superintendent of the building whom they think he knows more than he's telling them.

Simone and Sipowicz investigate a break-in of a high-rise apartment where the wife and baby are killed and the husband injured. Vince Gotelli, now an insurance adjuster, tells Simone and Sipowicz that the man may have faked a break-in to kill his family to collect an insurance policy. Meanwhile, Fancy gets some clues about a 15-year-old unsolved murder case from a visiting old friend who is dying. Also, Russell, Martinez, and Medavoy investigate the murder of a record company executive who wasn't very popular among his co-workers.

Sorenson and Sipowicz investigate when a fellow officer shoots a drug dealer; Russell and Kirkendall intercede on Gotelli's behalf when a disgruntled man repeatedly vandalizes his mobster neighbor's car.