A man and a woman are stabbed during a supposedly romantic park encounter. The woman's head as well as her hands are missing, which makes it difficult for detectives Benson and Stabler to identify the victims. They soon learn the crime scene was staged and that the woman was an officer of the Manhattan Federation for the Prevention of Cruelty to Animals. This leads them to various people from her organization, as well as its opposers, and a young sociopath (Michael Pitt) who had a troubled relationship with the woman.