A body on the beach is cause for concern, but the addition of a dead shark takes the latest case for Det. Mac Taylor (Gary Sinise) and his team to a new level. When Det. Don Flack (Eddie Cahill) noticed strangulation marks, he knew this would not be a simply death by chomp.

Back at the lab, Dr. Sid Hammerback (Robert Joy) confirms strangling. He also mentions carbon monoxide played a part. After another death in like manner, Det. Stella Bonasera (Melina Kanakaredes) adds a piece to the puzzle. Both female victims were real estate agents. Stella had sought out the first, Chrissy Watson (Kelly Bellini), after Stella's apartment building caught fire ("Right Next Door").

Quinn Shelby (Kristin Dalton The Dead Zone) arrives, checking out the lab for re-accreditation. The case at hand has to come first, inspection or not. Someone has killed twice, and must be stopped before another falls prey.

Det. Danny Messer (Carmine Giovinazzo) and Det. Lindsay Monroe process evidence. They have yet to discuss the state of their relationship. Danny says they could rent a movie, but Lindsay leaves the lab without giving him an answer. Quinn notices and mentions it to Mac.

This is the only cause for professional concern. She tells him the team surpassed expectations. Quinn's presence becomes invaluable when she is able to tie in an old case to Mac's. Stella and Mac figure out the killer targets people prominently advertising their services.

After a fourth corpse turns up, Mac tips off Reed Garrett (Kyle Gallner, Big Love), who works for a city paper. Rather than a column, Reed has a blog. He writes up a piece for instant publication while Mac and Flack decide all deaths are linked.

Okay, story ideas must be slow. This has been done before, with Shane Casey. The difference is the cops knew who he was before he escaped from custody ("Hung Out to Dry"). The killer is a cabbie, but that's all that is known. Did the chocolatier do it? It certainly doesn't make sense. Could be a woman....

The visual image of the killings was unsettling. However, no gore helped.

Mac and Quinn kissed? How charming! If Lindsay were ever to leave, Quinn replaces her nicely. The dialogue between her and Sid was solid. Ever better were the conversations between Reed and Mac. I have a feeling Reed will be useful.

Due to programming purposes, this story is not over. The shortest time viewers could see the end of this is two weeks. Less than ten episodes finish out the season, and this was the third.