DCI Barnaby's former colleague Jack Colby left the force under a cloud following a sex scandal involving villagers and officers at Causton police station. Now retrained as a probation officer, Jack is working at a halfway house for reformed criminals run by Lord Holm, an aristocrat who once served a prison sentence for killing his wife. However, when Jack is bludgeoned to death, Barnaby sets out to discover who murdered the man he once considered a friend.