The mermaids singing: "A serial killer is on the loose in the northern city of Bradfield. Four men have been brutally killed by savage knife wounds. In each case, the men have been mutilated and tortured, though the mutilations are not identical and nothing obvious appears to connect the victims. Fear grips the city; no man feels safe. Clinical psychologist Tony Hill is brought in to profile the killer, to work alongside Detective Inspector Carol Jordan."