This episode starts off with a couple running along a beach and taking of their clothes. They then stumble across a dead shark and a dead body. At first it is thought that the shark killed the woman, but Flack soon points out that she has a broken neck. Stella thinks that she knows the victim as her face looks very familiar to her but she can not place her. Also in this episode Quinn Shelby observes the team at work to determine if the lab should get their annual accreditation.
During the autopsy it is also discovered that the victim was poisoned. Danny says to Lindsay that they should rent a movie together. Perhaps their relationship can be fixed after all. Another victim is found. Stella then realises how she knows the 1st victim, she is a real estate agent. Stella has met her, because she is looking for a new apartment after her last one was ruined in the fire from the previous episode. Also Claire's son Reid also re-appears in this episode as a reporter. Claire was Mac wife who was killed during the attacks on the twin towers. It is discovered that both victims had chocolate in their stomach and the blend of chocolate is only available in a new fashion show. They go there but everyone denies knowing them. Lindsay discovers that they were poisoned in a boot of a car but the 1st victim woke up and tried to escape and that was why she was strangled. Shelby lets Mac know that where she worked also had a similar case a few months ago.
Mac also discovers that the scratches on the victims' necks may have been a message form the killer. Only problem is the 1st victim which was attacked by a shark in New York, has that part of her neck missing and also the team open up the shark to try and find the missing pieces. L2729 is carved into the victims.
Charles from the chocolate show is called in as a suspect. We learn that Shelby & Mac kissed once and she still has a thing for him. Mac discovers that the killer picks his victims through ads on the streets (billboards) which say things like "Come home with me" etc. The signs even go in order of death and so the team believe that they have found the next victim. Before the team can get there, he is there.
Mac & Stella pass the killer as they enter the building; he goes outside to try to get a cab. But she is still alive. When they enter the apartment where he next intended victim is, they find that she is still alive. They also discover that the stuff under the nails of the victims is from the passenger bill of rights. The killer gets into a cab, and when he tries to leave he finds himself locked in. Then the Passenger bill of rights is shown and what look like scratch makes can be seen on it. But was he the right killer. It then becomes obvious that the killer drives a cab; the person we thought was the killer is the next victim. And so we watch him die. They then find the body. Mac says any New Yorker could be his next victim. Will they ever solve the mystery of who the killer is, or will it never be solved for us the viewers. Overall a very good episode and very gripping. I loved the twist at the end of it.