Bolander asks Kay if she would double date with him and Linda, to try to take the pressure off his first real date. A slain phone-sex operator is found clutching a note naming her boss as the perpetrator, Bayliss and Pembleton investigate. Munch has trouble dealing with Bolander's happiness, so he crashes the double date and makes everyone miserable. A man is shot to death over a pen at the library, Lewis and Crosetti investigate and find a man with a pen fetish. As Bayliss looks into the murder he begins to get involved.

A young man comes into the squad room and after getting their attention, tells the detectives that his brother has been shot. Pembleton is sued by the multiple personality serial killer, who states he violated her civil rights during interrogation; he is discouraged when the city agrees to settle out of court. Munch must attend an alcohol awareness seminar to meet a requirement for the bar. Lewis has ""love at first sight"" with a woman who makes models of crime scenes, but she has ""love at first sight"" when she sees Bayliss and he sees her. Later, they attend an art exhibition and have an unusual sexual encounter in her ""bed."" All is not well at the Felton household, when he returns home to a cleaned out house.

Russert's old partner joins the homicide unit, but she suspects that he is taking his work frustrations out on his wife. Pembleton struggles with his pride and domestic life as Gee and Bayliss try to convince him to return. Bayliss is partnered with Lewis and on the way to the crime scene gets the ride of his life. Bayliss tangles with a reporter. Beau is in Philadelphia with his kids. The bar has its grand opening.

Pembleton receives an extradited prisoner from New York City Detective Logan. Bayliss is put in charge of investigating the death of Gordon Pratt, but gets no cooperation from anyone on the force. Beau wants to return to active duty. A woman recognizes Munch from an old picture that is hanging in an art gallery across from the precinct. To Munch's embarassment he discovers that an old girlfriend, who's a photographer, is displaying an old picture of him in the buff at her gallery showing. Pembleton and Meldrick investigate a random shooting of a woman, and they clash over where the weapon may have been fired. They also find a woman who's shot her boyfriend and stuffed him in the freezer. Beau accompanies Gee on an investigation and must come to grips with his inability to look at a dead body the same way.

The entire squad is put on 24-hour surveillance when a mass murderer has been identified, isn't at home and doesn't know that they know. Gee debates leaving the squad in the midst of the stakeout, so he can attend his daughter's wedding in California. As the detectives rotate through shifts on the stakeout, the main topics of discussion are the homeowners and Bayliss' plans to leave the unit.