After uncovering the fact that an elderly woman's tongue was cut out, Kay decides it is time to take a vacation. She returns home and while she is there she looks into the murder of an environmentalist. The suspects include her brother, an ex-beau and their co-worker. Pembleton reluctantly becomes Felton's partner and they finish investigating the murder of the elderly woman. Munch is against having a television put in their bar.

Munch spreads his usual Christmas cheer. Russert, who misses detective work, joins Meldrick on an investigation into the murder of a material witness, when she discovers she knows something about the victim's case. Munch and Bolander investigate the death of a man in a Santa Claus suit and Munch spends the evening with whom they believe is the victim's son. Beau buys Christmas presents for the kids, although he still doesn't know where Beth and the kids are. Bayliss searches the station in search of a game of hearts.

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.

A trash-talking radio talk-show host makes a proposal to his listening audience. Lewis announces to Kellerman that he is getting married today, then he throws up. He motivates the rest of the squad to help him with the final details as he is getting married ""tonight after the shift ends."" Kay brings her sister with her to the station. Since the whole squad is busy with Lewis' wedding, Gee takes Howard out to work the homicide of the radio talk-show host. One of his listeners took him up on his proposal. Munch is skeptical about the Lewis wedding; he thinks it's an elaborate practical joke. Bayliss and Kellerman vie for the attention of Kay's sister. Gee shoots and kills a potential suspect, but the suspect was in jail at the time of the talk show host's murder. The guy who fingered him admits that he did it as a joke. The wedding is no hoax. During the festivities Pembleton's wife goes into labor.

Family members of murder victims (Widmer, Rath and Silvio) are in a support group where they discuss their feelings about the loss they have each suffered. Short-handed, Gee investigates the Widmer homicide at the Waterfront Bar. Bayliss' homicide is unidentified for 48 hours before she is identified as being Rath. Lewis and Munch investigate a car jacking at Federal Hill, where the mother is the victim and the 3-year-old daughter in the car at the time is missing. Meanwhile, Howard, Kellerman and Pembleton stay behind. Frank interviews the two witnesses that Tim had in for questioning and gets a lead on a suspect. Cox joins the support group meeting late; she is still coping with the death of her father.