While investigating the murders of four teenage girls, the 15th squad discovers the shocking truth about the disappearance of detective Danny Sorenson.

Sipowicz is hailed a hero after killing the man responsible for Sorenson's murder. While Lieutenant Rodriguez teams up with another precinct to investigate the robbery of his mother, the squad investigates the murder of two men affiliated with NYU.

The squad investigates two homicides: the immolation of a would-be musician and the stabbing of a socialite. The newest detective to the squad, John Clark, Jr., attempts to both learn a new job and fit into the squad despite interference from his father.

The squad is joined by Eddie Gibson who's been transferred from nightwatch. McDowell and Gibson investigate the murder of a woman with MS, while the other detectives investigate the killing of a Rikers corrections officer.

When Clark's badge is stolen, the squad scrambles to find the thief before Clark must report the loss, which could ruin his career. McDowell and Gibson investigate a murder involving a young pregnant girl.

The squad investigates the theft of a baby from a hospital, and the arson of an Arab-owned business.

The squad investigates the murder of two drug dealers, and the discovery of a body mistakenly listed as a victim of the World Trade Center attack. McDowell arrests the daughter she gave up for adoption.

Sipowicz and Clark investigate the murder of a hispanic worker, while Medavoy and Jones search for a puppy-knapper who stole valuable champion bulldog pups. McDowell gets a new partner--Rita Ortiz.

Sipowicz and Clark are assigned to work with John Clark, Sr. on a murder investigation. Two good samaritans run afoul of the law when the burglar they caught dies from a head wound.

Sipowicz, Clark, Medavoy and Jones investigate a double homicide at a Latino restaurant. McDowell and Ortiz contend with a possibly mentally unstable woman who's posing as a cop.

The detectives investigate two separate murders of a college student and a Latina woman. Sipowicz goes after Mrs. Hornby's business manager. Haywood finally makes a decision about her pregnancy.

Sipowicz, Clark, Medavoy and Jones investigate the murder of an unassuming teenager. McDowell and Ortiz search for the person responsible for firing a stray bullet that killed a three-year-old girl.

The detectives investigate the separate murders of two supposedly upstanding citizens: an ex-convict turned community activist and a doctor who donated time to helping drug addicts and prostitutes.

The detectives work to solve two murders: the shooting of a rising rap star and the shooting of stripper found nailed to a table. McDowell and Sipowicz try to define their relationship.

The detectives investigate the bombing of an abortion clinic that killed a guard. The squad gets a new lead on an old murder case. Ortiz's husband, Don, is murdered by his mistress' husband.

The squad investigates the murder of a young Chinese girl along with an alleged rape case. Irvin learns his father is dying. Clark tries to find a foster home for James Kilik.

The squad investigates two homicides: a gay man who hit his head after being punched out and another man shot on the street. Rodriguez is set-up by iab to take a bribe from an old friend.

The day's cases include an armored car robbery that left one guard dead, and the homicide of a woman whose body was found in a garbage truck; Sipowicz intervenes in the iab's case against Rodriguez.

The detectives investigate two crimes: the murder of a back-alley cosmetic surgeon and a violent rape; Clark finally takes Laughlin on in the boxing ring.

Sipowicz is taken hostage in an interrogation room by a suspect in the murder of a pot dealer and two of her friends; a suburban mom found with drugs in her purse appears to be covering for her son.

An unreliable witness and an overzealous detective hinder a murder investigation; a con artist scam leads the squad to a sex-slavery operation; McDowell agrees to join Sipowicz and Theo at a theme park.

Andy and Connie return from their week's holiday with Theo. A boy goes missing, and the squad is lead to a pedophile in the area. John meets with a lawyer about his father's estate.

McDowell and Ortiz investigate the death of a woman found in her apartment, where an ex-con neighbor is suspect. The investigation into Scott's murder points towards his friend. Andy thinks about the future. Rita meets John's father.

The temperature is rising. Andy receives a death threat. A prostitute is murdered, causing IA to look at John. A huge drugs and cash hoard is found. An elderly woman is found tied up and beaten.

A bomb threat is received at the courthouse. John Clark is placed on restricted duties pending charges for murder of the prostitute. John Irvin buys a new car only to be carjacked on the first drive.

Andy and John attend a shooting where a man is shot in the groin. Connie's sister turns up, pregnant and beaten by her husband.

A little girl disappears at the park, after her father leaves her - or so he thinks - in the care of a friend's nanny for a moment. Connie's brother-in-law is arrested.

A boy on a bicycle is murdered. Connie's sister posts bail for her husband.

Maya's partner in anti-crime is killed. A little girl is snatched off the street. Connie becomes foster-mother to her niece.

Connie struggles to settle with the baby. A woman is found dead in a vacant lot. Another is found dead in the laundry room of her building. The Lieutenant dresses up for a lunch.

When NYPD Auxiliary Police Officer Heather Peterson is murdered, the detectives find a diary of her's that details the sexual habits of the police officers at the 15th precinct. These findings cause the detectives to suspect the officers of the 15th precinct had something to do with her death, and the investigation of the cops cause tension between the officers and the detectives.

IAB start interviewing the officers who were in the diary, and Sipowicz and Clark are blamed as rats. A social worker appears to have taken her own life. A former cop wants his ashes buried at the precinct.

Andy and Theo move out. Tony thinks about calling it a day with his ex-wife. Sipowicz and Clark Jr look into the threats made to Clark Sr. A distressed, schizophrenic young man keeps saying "she can't breathe".

Connie and Rita find young children home alone, living in squalor. Tony's ex-wife is found dead. A carjacker is killed, and cocaine is found in the car.

Clark is placed under arrest after police find heroin in his car; detectives search for clues when a woman is beaten to death with a cordless drill; a murder victim's obsession with clean living may have led to his demise.

In hopes of freeing Clark from jail, Sipowicz searches for drug dealers who might have a connection to Laughlin; McDowell and Ortiz investigate a series of rapes in a park involving a perpetrator who forced his victims' boyfriends to watch.

The detectives investigate the murder of a gay man who gave room and board to Latino parolees in exchange for sex; McDowell and Ortiz search for clues when a community activist is stabbed to death.

A transvestite prostitute's murder leads the detectives to two prime suspects: a pimp, and a john who claims the pimp and the prostitute set him up in an effort to steal a watch.

Sipowicz and Clark investigate when Julian Pisano is wounded in a shooting incident; McDowell and Ortiz assist a woman who doggedly pursues justice when she's conned out of $100; Clark grows concerned when his father stops returning his phone calls.

Jones accidentally shoots a 13-year-old boy while pursuing a murder suspect; McDowell and Ortiz search for answers when a man whom police escorted from the scene of a domestic dispute is found dead.

The detectives investigate the murder of a gay financier whose death might be tied to a marine; Medavoy and Jones search for answers when a strangler attacks a Russian mail order bride; Haywood feels threatened when a murderer's conviction is overturned.

As Andy and Connie prepare to finalize the adoption of baby Michelle, Frank Colahan's mom and dad show up. Connie sweetly and sincerely tells them they want the grandparents to be part of Michelle's life to the fullest extent possible.

The murder of a man who frequented a betting parlor leads Sipowicz to an old friend; Jones searches for the man who attacked Haywood; the detectives research the Colahans' background.

A meek and mousy young woman is found beaten to death on the floor of her apartment. Her brother- in-law is very upset but not about her death--he was paying her money to use her apartment for an extramarital affair.

The detectives hunt for a man suspected of killing minorities to avenge injuries his brother suffered during the first Gulf War; Sipowicz and McDowell plan to marry.

The detectives investigate the shooting death of a man whose brother is a registered sex offender; and when Captain Fraker's trial gets underway, Sipowicz worries that his own testimony may have harmed the prosecution's case.

Sipowicz and Clark investigate the death of a transvestite whom a friend insists was having a relationship with a married man; a surgeon's hand is badly cut during a robbery; and Rodriguez testifies in the Fraker trial.

The detectives search for clues when a group of perpetrators torture a man for no apparent reason; a woman reports her husband as missing, but Sipowicz and Clark suspect she's not being completely forthcoming; and Fraker testifies in court.

The detectives investigate the strangulation death of a former porn star; a thirteen-year-old boy holds the key in implicating his father in his mother's murder; and the jury reaches a verdict in the Captain Fraker trial.

The detectives investigate a strangulation murder that may be tied to one of Diane Russell's cases; Russell consults a doctor when she discovers a lump in her breast; Medavoy and Jones investigate an arson linked to two boys.

Sipowicz, Russell, and Clark attempt to connect the murder of a young woman to two other killings; Medavoy and Jones investigate the shooting death of a mother whose children feared her.

A woman survives the serial killer's attack, and her account prompts the detectives to focus on Carlin, his partner, and a bodyguard; Medavoy and Jones investigate when an off-duty officer kills a man; and McDowell comforts Russell during a biopsy.

When another woman is murdered by the serial killer, the detectives arrest a suspect... and discover the killer's identity; and expecting a baby, Sipowicz and McDowell decide to get married.

Sipowicz and Clark search for two burglars who terrorized a retired cop and his wife; Medavoy and Jones assist an author who wrote a book on how to avoid paying income taxes; and Jones deals with Michael's father.

A man armed with a bomb walks into the station house and handcuffs himself to McDowell; unless the detectives release a Russian mobster from jail in one hour, the bomb will detonate.

When a Jewish jewelry-store owner is murdered, the detectives focus their investigation on two suspects: a Caucasian man who converted to Islam, and a rap star whose expensive jewelry turned out to be fake.

Sipowicz and Clark search for an African-American driver who fled the scene of a hit-and-run accident after unwittingly running over an Italian mobster's young daughter.

Sipowicz and Clark investigate the shooting death of a jogger who'd been having an affair with a police officer; and Medavoy and Jones search for answers when the body of a comedy club owner is found in the trunk of a stolen car.

A new detective, Stan Hatcher, joins the squad; the detectives investigate a shooting death that Hatcher believes is linked to a dispute between gang members; and a man insists that his young daughter has been kidnapped.

A kidnapping victim's startling statement clues Andy and John in on a serial sadist keeping women locked in a dungeon somewhere in New York. Meanwhile, a routine robbery investigation takes a saucy turn for Medavoy after he makes an unlikely connection with the 60-year-old victim.

Sipowicz searches for the truth when Hatcher is shot by a man who mistook him for a burglar; and a former pharmacist dies in a flophouse when someone fires a bullet into his room.

Andy's off-duty and slightly underhanded work to prove that Hatcher killed his own wife lands him a transfer out of the 15th precinct and into the Bellevue Morgue engineered by Detective Hatcher. Meanwhile, the squad is up to their whips and chains after a dominatrix is found murdered.

Haywood reopens an 18-year-old case that has Andy reliving a major mistake in his career. Meanwhile, Sipowicz and Clark investigate the death of a man whose brother was pursued by a bounty hunter. Elsewhere, Ortiz gets a new partner, Detective Kelly Ronson, who ends up lending an unusual hand during the hunt for the child an ex-con had to give up before going to prison.

A man's gunshot-induced amnesia causes Jones and Medavoy to concoct an unconventional way to nail his assailant. Meanwhile, a man Sipowicz put away twenty years ago for raping and murdering a 12-year-old girl goes free after DNA testing exonerates him, and Ortiz and Ronson bust a gruesome underground network pre-teen prostitution ring.

Andy and John approach Mrs Clifton for help with her daughter's murder. Jennifer turns up out of the blue, apparently off her meds. A man is shot, apparently over a church and a video tape.

A face from Clark's past makes an unwelcome return, while the key suspect in Andy's 18-year-old murder case turns up, face down. Jones helps Michael prepare to take the stand against his own father for killing his mom, and a man fears that his wife is going to lose her head after he loses her pricey necklace.

Sipowicz investigates a murder involving the victim's current husband and ex-husband. A longtime informant gives Ronson information about an illegal gun shipment, but the suspect's father is being followed by the FBI. Jones gets into a fight with Craig after he's acquitted of murder charges, and Sipowicz is the proud father of a baby boy.

There's a new boss who comes from IAD with a mandate to clean up the squad. Andy receives a dead rat in the mail. John is heading off the rails. A doctor is found dead, and linked to a man who had a sex change.

The detectives tie the death of a pregnant woman to an adoption scam; Medavoy and Jones interview a woman who claims a masked assailant stole her valuable ring; and someone poisons Sipowicz's beloved fish.

When a convicted rapist is found shot to death, his victims become suspects in the murder investigation; and Sipowicz searches for answers when a stranger targets Theo as he walks home from school.

The detectives investigate the death of a phone-sex operator and the kidnapping of a wealthy man's son; and Clark's tryst with a murder suspect is used to derail the prosecutor's case.

After being shot outside a bar, Sipowicz discovers the identity of the person who's been harassing him.

While investigating a random stabbing, Sipowicz becomes obsessed with his own mortality after he's nearly gunned down by a murder suspect; Medavoy takes a job as a bouncer.

The detectives protect a scared witness testifying in a felony murder trial; Michael's father wants to regain custody; Bale finds out about Medavoy's job at the bar.

A gunman tries to kill a witness after a mistrial is declared in the Simon Kerensky arson case; and Jones goes to extremes to stop Craig from adopting Michael.

Jones becomes a murder suspect after Michael's father is shot to death; and Ortiz and Murphy investigate a molestation case that might involve a priest; Medavoy gets his hearing in trial court.

A man who cared for his brain-damaged brother is found dead; Medavoy falls for a wealthy woman while investigating an apartment rental scam; Bale tries to nail a man who offered the detectives a bribe.

While investigating a murder, Sipowicz discovers a secret about Bale; and Ortiz and Murphy investigate a shooting tied to a talented up-and-coming basketball player.

A call-girl's death is linked to other murders involving women who'd gone through rehab; Ortiz and Murphy investigate the death of an artist who'd been carrying on an affair with a wealthy man married to two other women.

The detectives continue their search for a serial killer who targets alcoholics trying to get sober; and Clark and Jones investigate a homicide linked to a woman with whom Clark had a one-night stand.

Sipowicz and Clark investigate the stabbing death of a coffee-shop owner who was attracted to young girls; Ortiz tries to keep her cousin out of trouble; and Medavoy and Jones link a murder to a paralyzed police officer and his family.

The detectives search for a suspect who killed a businessman by blowing up his car; and Ortiz and Murphy investigate the beating death of a student.

The detectives investigate the smothering death of an elderly man married to a voluptuous woman in her 20s; and a state judge pressures Medavoy and Jones to find out who poisoned her mother.

As Sipowicz settles into his role as sergeant, the 15th finds his absence unsettling, especially after Clark is teamed with a hair-triggered military officer on the murder of an Army man. Meanwhile, Jones and Medavoy's search for a missing homeless man leads one of them to a bold move.

A squad member is shot while storming an apartment; Clark and Jones investigate the bludgeoning death of a woman whose wealthy husband was going to finance a friend's salon business.

Bale offers to recommend Sipowicz for the squad commander position; Ortiz and Murphy investigate the death of an Arab woman; and detectives search for the man who shot Bale.

As he begins his new job as squad commander, Sipowicz disobeys orders and keeps a murder investigation open... even though a Japanese man with diplomatic immunity has confessed to the crime.