The body of a young woman has appeared on Rockaway beach the CSI team is called out to investigate what exactly happened to the woman. Mac and Sheldon arrive to begin investigating the death of this woman. Mac tells the team assembled that may have a shark attack victim and it's more of a job for the coast guard not for his team. Detective Flack tells Sheldon to take a closer look of the body. Sheldon sees that her hand was the shark's appetizer and that there is bleeding in the eyes.
Detective Flack also tells the team there is currently no identification on the victim. Sheldon also finds strangulation marks around the victim's neck causing everybody to wonder why a shark would strangle its victim before taking a bite.
Stella, Mack, and Hawkes all began photographing the scene Stella is taking pictures Hawkes is analyzing the body and says that the femoral artery was somehow punctured there is a lot of blood loss from the victim. Sheldon said there was major tissue damage. Stella tries to figure out one someone would be strangled first and then tossed to a shark. Stella continues to stare at the body Sheldon continues explaining that the injuries he sees postmortem.
Stella tells Sheldon she can't place the woman but knows she has seen her somewhere.
Mac is busy looking at the tiger shark and touching it's carefully and noticing red spots are all long it. Quinn Shelby who applied for the job he has now has come from her lab in New Jersey two give Mac's lab reaccreditation.
Quinn Shelby starts telling Mac what those red spots on the shark are. She also tells Mac she will quietly observe the team. Mack tells her he's never known her to do anything quietly.
Quinn tells Mac every few months she files a report for the forensics board on whether labs should be reaccredited. She states that it has been five years since the lab was reaccredited.
In the morning Sheldon is busy cutting open the tiger shark and he mentions he found the victim's hand in the sharks elementary cannel He mentions the topography rips are a match to the victims wrist. The medical examiner mentions that tighter sharks are the wastebasket of the sea and second only to humans in terms of shark attacks.
The items recovered from the victim's stomach were some kind of handle and in another bag is something they aren't sure what it is yet. The medical examiner hands the stomach contents to Mac to go through. The medical examiner also mentions that he found blood in the victim's lung tissue. Sheldon wonders if this was a failed attempted suicide or hanging and she decided to jump.
Mac believes this could be a failed attempt to murder. Mac also believes that victim number one was likely poisoned first and then strangled. The medical examiner in his interesting sense of humor tells the gentleman a completely different story he figures everybody should feel sorry for the shark because he was eating the finest meet he had in while so because of the blood found in the one tissue the victim killed the shark the cause of death for victim number one is strangulation.
Quinn is busy carefully watching Stella as she analyzes the victim's stomach contents. Stella is a bit nervous because most people are intimidated by her job. She mentions that the substance she is looking at is crystals. Stella does a morphological search on the crystals that appear to help chocolate when it's eaten. The morphological search turned out to be some kind of drug that he is used to enhance lovemaking and lucid dreaming. As the morphological search continues Stella asks how Quinn knew Mac. She mentions they both applied job that he currently holds.
Quinn tells Stella the crystals look like cocoa butter seeds when the chocolate is agitated.
Quinn wonders if Mac through Stella some kind of a curveball that she didn't know about. Stella tells her he didn't both women agree about a good drink. Sheldon is busy liquefying the stomach contents in a blender. Lindsay and Danny are busy analyzing evidence but Lindsay is finding it hard to be around to Danny. To break up the tension she begins quoting a line from Jaws Danny tells her she's not good on the accent to so they end up quoting the whole line together. As they do this inspector Shelby is busy writing her report while watching Denny and Lindsay. A short while later Lindsay tells Danny this is too hard and leaves evidence unattended.
Sheldon, Stella, and Mac are in his office as they update the latest in the case so far. Stella mentions that phosphine was found in her skin and in the stomach contents that Sheldon liquefied. A few minutes later Lindsay comes in and tells everybody that she found a gravestone. Mac gets a telephone call about another body. Danny, Sheldon, and Stella still discussing what the result of phosphate might mean. Sheldon can't exactly figure out what made the blood found in the first victim bright red Stella believes that it could be carbon monoxide because the medical examiner found it.
Mac tells Stella they have another body the body was found a mile away and from the Rockaway victim. The victim looks familiar although there is no ID on the victim. Stella listens as Detective Flack mentions he found something on the victim. The victim's name is Louise Perry. Stella had seen her when she went to the real estate office to look for a new condo. Detective Flack and Mac both believe that two victims found in 24 hours is not a coincidence
Mac and Stella are busy trying to go back in the lab before reporters can ask them questions about the latest on the case. Reed calls out to Mac to see if he can get any information on the case for his blog that he told people he would promise to get that information exclusively.
Mac tells Reed that if you yell murder in the city people don't even blink if you yell serial killer people panic Mac tells Reed that this is psychological. Mac tells Reed about the latest in the case two women were murdered with the same MO.
Mac tells Reed that the next time he has something important to tell you he will be the first to know. Quinn tells Mac he has a great team she is concerned Lindsay and Danny are more than just co- workers. Mac says he never gets in the business of his team's personal lives. Quinn tells Mac the evidence was left unattended by Lindsay and that if the relationship affects her job things will get sloppy.
The medical examiner says that Louise Perry died due to carbon monoxide poisoning. The medical examiner shows Mac and Quinn that there were some marks inflicted on the victim postmortem. The medical examiner comments that he doesn't often get enough guests in the morgue he still has the shark on ice if she would like to take a look at it.
Mac tells the medical examiner that inspector Shelby is here to supervise the documenting of the evidence. She tells Mac and the medical examiner than she can't speak to motive but can take a look at the tox report. She asks Mac and the medical examiner if there was anything similar between Louise Perry and Chrissy Watson the first victim. The medical examiner mentions he found an adhesive under the victim's fingernails.
Both were strangled by a shark and blood was found in the tissue and they had strangulation marks. Both died of Co. poisoning. The inspector takes a look at the tox report and says that based on the evidence and due to the carbon monoxide levels she concludes that the victims were trapped in a confined and small space that would attribute the levels of carbon monoxide they were seeing. Also both victims had ingested chocolate. The inspector tells Mac that he could be looking for a land shark. The medical examiner tells the inspector that she is very good making Mac feel suddenly left out. Danny is busy trying to find Mac to tell him that phosphine is found in fumigation. Currently there are 235 buildings in New York being fumigated. Stella tells Mac that the drug they found in both their victims is also found in Creole which is a very expensive dark chocolate that is currently not on the market yet and is being debuted this week.
Stella and Detective Flack are busy looking for a girl who is on the runway. And while there doing this Detective Flack asks about the inspector. He wonders if she is pretty. Stella says the situation is rather weird because Mac seems OK with the inspector she also tells Detective Flack that the inspector knew Mac quite a while ago.
Flack and Stella find the girl they are looking for. They also the interview the guy that is selling the chocolate Detective Flack presents the chocolate guy with the pictures of two victims and he asks if he knew both of them. Stella is offered a sample of the candy but doesn't take any from strangers.
When they interview the chocolate guy he tells them that they all had an access to samples of the chocolate.
Mac Taylor walking over to Lindsay after having just gotten her cell phone message. The evidence she shows him is a trunk handle that allows someone to open the trunk from inside. Lindsay asks Mac to shut the trunk of the car with her inside. She tells him it's OK. Mac helps Lindsay out of the trunk and she begins to explain that the trunk and all these found on cars made in the year 2002. Mac figures that there was one problem Chrissy Watson didn't fight back she tried to get out but was unable to because the killer saw what she was doing. They figure that in order for her to fight back inside the car she didn't get enough carbon dioxide poisoning to kill her.
Mac then points out Lindsay left evidence unattended. Lindsay says Danny was right there she was sure he had put away. Mac doesn't buy the story. Lindsay tells Mac that that was a bad excuse to use and realizes that could put somebody away for murder. Mac for the moment doesn't care about that he tells Lindsay he's just more concerned about her. And tells her that whatever is going on between her and Danny not to let it affect your job and deal with it on her own time.
Inside the New York crime lab Reed is rather upset because he didn't get the exclusive he was promised on the case. Mac tells read you shouldn't promise people something he can't give them. Mac is handed a copy of New York weekly and is told that a story didn't come from him.
Mac doesn't want to use case two further their relationship. He tells Reed that when he has something important to tell him he will be the first to know. Just as Reed leaves inspector Shelby arrives. Mac wonders if this could be about Lindsay again. Inspector Shelby called her lab in New Jersey and did a little digging and found a fourth victim. She shows Mac a picture of the victim's skin with some writing on it. The victim's name is Ben Melvoy.
This makes Mac want to check further into the sharks' intestine and see if there could be any more evidence in there He calls Sheldon and asks him to meet him in autopsy. Mac thinks the killer is trying to say something question is what is it?
Mac and Sheldon are both in the morgue getting ready to pull more evidence out of the shark's intestine they find that the shark had eaten more than they realized. What they pull out of the shark it has a letter and a number on it. L2729. At the AV lab Mac asks Stella to find out what that number means and to go outside the perimeter of the lab. Sheldon mentions that he found slate in the shark and gravestone which means that the killer likely used gravestone to carve something. Sheldon helps Lindsay on the trace because she is analyzing it further to see what else it might tell them.
Stella tells Mac that she might have an answer as to who Chrissy Watson knew the night she died them and then knew her one Charles Khol Interpol issued a red letter on him and he was charged with sexual harassment. Mac begins to wonder if Charles Kohl has more than one signature.
Detective Flack and Stella begin to interview Charles Kohl. He tells them he didn't know Chrissy Watson. Stella pulls out a signature log that indicates he was at Christie's open house the night she died she then points to his signature right on the log.
Carol tells them she was sending him mixed signals when the flashback shows he was he was trying to kiss her and she didn't want it. Charles also tells that he was being pressured to buy an apartment when he was looking for a $5 million.
Detective Flack pulls out pictures of Louise Perry and a picture of a lawyer from New Jersey he asks if Charles knew those people he claims he didn't. Stella points out he was in New Jersey three months ago.
Hawkes and Lindsay are busy analyzing the evidence that was collected earlier Lindsay found sycamore and ash which leads them to saint Anthony's church. Sheldon also mentions that there was an article in the paper about the tree branches that saved the church from being damaged due to September 11th.
Quinn tells Mac that she still has a thing for him and she hopes that they can rekindle their relationship. Mac tells her that because the kiss they had together was a mistake. He also tells her that he loved his wife Claire and that he was married. Quinn wonders if Mac ever wonders what would've happened if it hadn't been a mistake. Mac tells Quinn that no matter how good the memories are they are best left forgotten.
Stella, Mac, Sheldon and Detective Flack all meet St. Anthony's church to discuss what they have so far. Detective Flack mentions that he showed a picture of the suspect no one knows who the suspect is. Sheldon can't figure out why a killer went do so much damage and not leave a piece of himself behind. Mac requests that Sheldon get a sample of every gravestone in that church. And that Detective Flack interview everyone in the congregation because the suspect could have been a member of that church.
Stella also mentions that the number she is trying to do research on at this point doesn't lead up to anything. She goes over when the victims were killed. Louise Perry was killed three months ago then Chrissy Watson and then Ben Melvoy.
As they ride back to the lab Mac begins to spot something rather odd he spots posters with their phone numbers Louise Perry, Christy Watson, and not too far up the street could be the next victim P.J. Davis. Mac figures out that the way the killer is taking his victims is in the order of their deaths.
Mack and Stella are given the address 2352 Park Avenue a man is found in that particular apartment with real estate agent P.J. Davis. He can't seem to get a cab. Stella and Mac arrive at the apartment while the man is still trying to hail a taxicab he finally does we noticed the cab driver inside messing with some controls so the windows can't be opened. Inside the apartment Mac and Stella carefully look for anyone inside they find real estate agent P.J. Davis still inside she asks if she can help them. At the lab Danny and Lindsay still can't figure out what was under the victim's fingernails. Lindsay then goes to the computer and types and some words soon the search comes up with the taxicab bill of rights which tells what passengers are allowed to have. Danny calls Mac and what they found under the victim's fingernails taxicab bill of rights. As Mac explains that the carbon dioxide is forced into the cab through the tailpipe and just as soon as a passenger realizes something is wrong it's too late. The driver in the cab doesn't hear the passenger yelling for help. We believe the passenger in the can still trying to gasp for air In the final scene a sixth victim is discovered with this same marks on the body Mac Detective Flack and Sheldon all examining the body. Reed types in his blackberry autopsy report. Mac than requests than Detective Flack get a list of every taxi cab driver in the city with their records and Detective Flack reminds match that there are at least 11,000 cabs in New York City Mac tells Detective Flack that the taxicab driver and any New Yorker could be his next victim.