Russell worries about her mother's pending grand jury trial for the intentional murder of her father. Meanwhile, Sipowicz and Simone search for the killer of a mobster's son, that reveals a family affair. The pompous lawyer of a suspect in another murder case impedes Medavoy and Russell's investigation and the erratic behavior of son of the victim doesn't help much either. Also, Martinez and Lesniak investigate another murder case that may be connected to Sipowicz and Simone's murder suspect who now may be on a killing rampage.

A detective from another precinct, Martina Escobar, joins Simone and Sipowicz with their investigation of a rapist/murderer who is throwing small children from the tops of buildings. Meanwhile, Martinez and Russell investigate an alleged case of date rape, but the women of the squad and Sylvia have a major disagreement with Martinez's decisions regarding the suspect. Elsewhere, Sipowicz shows his son the ropes of being a cop.

Simone makes contact with Ferdinand Hollie, an old informant, who wants to help him capture a pair of Colombian drug dealers who killed a young girl with their crossfire. But Hollie, a drug addict who is HIV-positive, has his own agenda to rob the Colombians. Meanwhile, Russell is paired with Sgt. Ray Kahlins, a "blowhard" from the federal anti-drug unit who is more interested in collecting overtime pay than catching a separate pair of drug dealers during a stake out. But Kahlins' brash tactics and disrespect for Simone and his informant Hollie, put both cases at risk. Also, Medavoy and Martinez investigate the murder of a Santería priest found in a local sewer and try to link a parole officer and a recent parolee to the crime.

Simone and Sipowicz investigate a story that a diamond dealer and his partner report that one of the dealer's sisters is missing with a bag of diamonds worth a million dollars, but the sister's boyfriend is actually responsible. Meanwhile, Martinez, Medavoy and Russell look for the assailant of Gina who badly slashed her face up while she was on her way to work, and Martinez cannot cope with this sudden turn of events. Simone and Kirkendall go out on their first date, while Russell cannot cope with the fact of being alone again.

Richardson confronts Sipowicz and Simone about their impending questioning of his wife over the murder of the nurse, but with the exception that Richardson is a real bad person, Sipowicz and Simone reach nothing. In a cross-over from the series "Upstairs", former temp and private detective John Irvin stops by the station to tell the detectives about the new graphics art business he started. But with the exception of the receptionist Dolores, no one is around, including Medavoy who leaves in a hurry for upstate New York where Abby now lives to be by her side when she goes into labor. Meanwhile, Kirkendall and Russell look into the theft of a graduate film student's camera, where only the student seems more interested in dispensing his own justice. Also, Sylvia finally learns about Sipowicz's medical condition from his doctor and finally persuades him to go for further tests and possible surgery.