When a beautiful girl is murdered, dragged in a dumpster, the unit investigates the case, but it's difficult without a clue except of a white glove found on the hand of the victim.

Still investigating the murder of Catherine Goodrich, another victim is found with the same clues and Frank is now the primary on the case. Felton is thinking about going back to his wife, Munch and Lewis consider to buy a tavern.

With another girl found dead with a glove on her hand next to a Catholic Church, Frank questions his faith but then a witness might help the detectives find out the killer's identity.

Kay Howard becomes closer to John Munch when she realizes how saddened he is by children being involved in horrific crimes. Meanwhile Bayliss falls for a seductive closet-goth, Emma Zoole.

Gee investigates the murder of an old friend and Bayliss's relationship with the police artist turns sour.

The unit investigate the death of their friend and Lewis' partner, Steve Crosetti which appears to be a suicide, but Lewis is sure there is more to it than this.

Howard decides to go on a sudden vacation to her hometown, but soon she has to investigate a murder of a conservationist. Meanwhile, Frank has to fill the absence of Howard as the partner of Felton to solve a case.

It's Christmas time, and Lewis gets a case in which the victim's identity is unknown due to heavy burns. Munch and Bolander deal with the death of "Santa" but nothing seems to ruin Bolander's Christmas spirit.

Bayliss and Frank investigate the murder of a kid who was shot in a bowling alley. Felton gets a clue about his family's whereabouts.

Lewis and Munch investigate the death of Andrew "Monk" Whetherly, a member of the Deacons Motorcycle Club. Whetherly's wife, Bree, leads them to Preacher, the gang's warlord, who says Monk was killed "because he loved his little girl."

Detective Douglas Jones, Russert's former partner, joins Homicide from Narcotics. Later, when Jones' wife Natalie is admitted to the hospital with suspicious injuries, Russert confronts Jones about possible spousal abuse.

Detectives Howard, Bolander and Felton are shot during an ambush and left in critical condition. Pembleton feels obligated to get justice, Munch becomes traumatized and shocked, and Giardello faces an investigation of his work.

The Homicide Unit captures Glen Holton only to learn that he wasn't the one who shot Felton, Bolander and Howard. Meanwhile Russert is forced to investigate Giardello's work to find out if he should be at fault for the ordeal.

Bolander has a relapse. The detectives sound off to the local news about the shooting. Apartment 201 is opened up and the occupant, Gordon Pratt, is a gun freak who once tried to be a cop.

Pembleton and Lewis investigate the random shooting of a woman, meanwhile Bayliss suspects Munch of going vigilante and murdering Gordon Pratt. Felton tries to get used to being back at work but finds getting around to be difficult.

Beau meets Megan's cousin, NBC's Tim Russert. Kay and Stan return to duty, after Stan undergoes a final test, and Kay finds her desk has been moved.

A 16-year-old murder case must be reopened when the daughter of the convicted killer holds Col. Barnfather hostage. Pembleton and Bayliss investigate an elderly man whose wife died of drowning in the bathtub.

Crosetti's caseload is distributed among the detectives and Howard's 100% clearance rate may be in jeopardy when she gets his most difficult unsolved case; this is further complicated when Beau misplaces some new evidence.

Tim's cousin shoots a Turkish exchange student and his partnership with Pembleton may be in jeopardy when they both stand on opposite sides of the case. Lewis hires his grandmother to cook at the bar.

A convict is released from prison and begins to get his revenge on Frank by frustrating the investigation he is currently working on and also by terrorizing his wife.