Briscoe and his new partner, Det. Reynaldo Curtis, investigate the murder of a young girl who disappeared between school and her music lesson, with a blurry film from an ATM machine as their clue.

Briscoe and Curtis have a hard time finding cooperative witnesses when investigating the murder of a college student at a rough biker bar.

McCoy and Kincaid clash over the death penalty as McCoy prosecutes a man who murdered an undercover cop during a drug bust.

A triple murder at a magazine publishing company leads to a case of sibling rivalry, a protective matriarch and a corrupt judge.

When the detectives solve a series of murders committed by a holdup team in ski masks, McCoy must determine whether a young woman found with them is an unwilling hostage, or an active participant in the crimes.

Briscoe and Curtis try to solve a co-ed's murder after a graphic description appears online, while McCoy finds himself up against a lawyer who is reluctant to reveal elements of her client's past.

The investigation into a prostitute's murder leads to a married plastic surgeon as the obvious suspect, but Kincaid has a hunch that an elaborate frame-up is in play.

A mother claiming that her baby was kidnapped while she was at confession retraces her steps and actions with Curtis, which raises legal questions later when her attorney introduces a unique defense.

A hidden anti-Semitic message in a high school yearbook offers a clue to an art teacher's murder and leads to a case that matches McCoy against "Klan lawyer" Roy Payne.

The victim in a 30-year-old rape and stabbing case is fearful when information received by Briscoe and Curtis creates the possibility of a new trial for the perpetrator.

The death of a show horse leads to a trial involving insurance fraud, a sting operation and a wealthy woman's disappearance.

McCoy finds that his career is on the line when his former female assistant and ex lover accuses him of forging evidence that helped put an innocent man in prison.

A subway station gas attack, similar to one that took place in a Baltimore church five years earlier, brings Baltimore detectives Tim Bayliss and Frank Pembleton to New York to assist Briscoe and Curtis. This crossover continues on Homicide: Life on the Street S04E12 For God and Country (II).

Paul Robinette places the system on trial when he defends a young black woman accused of kidnapping her biological baby from his white, adoptive parents.

A jogger killed in Central Park turns out to be the second wife of a former comedy club owner, who was acquitted of killing his first wife. And convicting him this time may hinge on tracing the path of a Columbian coin used as a subway token slug.

A down-on-his-luck ad executive becomes the prime suspect when his wife and son are killed, and his daughter wounded on a night that he claims was spent drinking.

The investigation into the murder of a model with a passion for cocaine and partying focuses on the men in her life -- a nightclub owner, a basketball player, a photographer and a limousine driver.

A woman is shot while sleeping, and the investigation leads the police to a boy whose crack-addicted mother has entrusted him to a dealer's care.

After a college co-ed's body is found, the detectives look for a campus rapist, but the medical examiner's report puts them on a different path, one involving prostitution.

The investigation into multiple homicides at a clothing store leads to the arrest of a schizophrenic who presents McCoy with a formidable opponent when he decides to represent himself.

After an infant is found dead in his crib, it's determined he was poisoned, and all evidence points to the child's au pair.

After Briscoe, Curtis, McCoy, and Kincaid witness the execution of a criminal they brought to justice, their unique reactions to the event culminate in personal tragedies for each of them.