 The team revive a 30-year old investigation into animal cruelty when a dog is found butchered on Hampstead Heath. The original investigation focused on John Fletcher, who was the press officer for The Human Liberation Front, an organization that was set up to counter the animal rights movement, but is no longer in existence. They seek advice from James Farlow, the animal control officer at the time, but have few leads. They determine that the killer may actually want to harvest the animals  vital organs. Meanwhile, Jack is feeling ill and is hospitalized with some unknown ailment.