Stephen Parnell, who confessed to murdering five people, is killed in prison, but in his dying declaration, he claims that he did not kill the last victim, Karen Anderson. Morse learns that the murders were first investigated by DCI Martin Johnson and Lewis the previous summer, but that Karen Anderson's body has never been found. Morse becomes convinced that Johnson overlooked key evidence, and that Karen Anderson's body has been buried in Wytham Woods, and not in Blenheim Lake, as Parnell had stated in his confession.