When Det. Stella Bonasera (Melina Kanakaredes) and Det. Don Flack (Eddie Cahill)
investigate a man's death, they do not realize they will soon be dealing with a complicated crime. The victim is dressed in a coat of armor, which could have come from any costume shop. A blood trail puts the primary crime scene in Central Park.
Little evidence is available to unearth the killer, but help comes from another crime scene. Det. Lindsay Monroe (Anna Belknap) and Dr. Sheldon Hawkes (Hill Harper) go to a fancy hotel room to find another man dead. The cause of death is clear, stabbing by icepick.
Although it is different from the chest wound the first victim had, Dr. Sid Hammerback (Robert Joy) discovers someone closed the eyes of both men after they died. It was a blond female who smoked pot, but they cannot narrow it down beyond that. Further investigation reveals a link to a support group for people with cancer.
The case finally comes together. The two men, along with the blond woman who helped to kill them both, made a suicide pact. None of the three wanted to live with their illness, so they each died as they most wanted.
Stella talks to someone who tried to stop the first two deaths, but couldn't. She says she did not take her own life because she chickened out at the last minute. The detective does not reveal anything about possibly being infected with HIV, but the conversation hits home. She goes to Det. Mac Taylor (Gary Sinise) and asks him to authorize a test for HIV. She knows it would be performed in-house, with the help of one of their colleagues. After a bit of thought, he agrees. Stella wants to live out her life to the fullest, HIV or not.
Mac has a crisis of his own after a corpse is stolen before it can reach the morgue. Dr. Peyton Driscoll (Claire Forlani) is hurt, but shaken. The call to Mac from Det. Danny Messer (Carmine Giovinazzo) sends Mac racing through the lab to get to his girlfriend, and to find out what went wrong.
Since Peyton was hit from behind, she cannot give a good description of the getaway vehicle or its driver. A suspect is soon located, but more evidence is needed to determine if he is responsible for the attack.