The Dark Rider Bentham DeQuetteville falls to his death from the roof of Quitewell Hall after seeing a headless horseman, but his aristocratic family seem more concerned about their forthcoming Civil War re-enactment than the tragedy. Betty, estate manager and second wife of Toby DeQuetteville, wants to find ways to gain income for the ancestral seat, not helped by the eccentric head of the family Sir Ludo and his wife Lady Izzy. Barnaby finds a priest hole containing a 17th century portrait of headless Cavalier officer Geoffrey DeQuetteville on a grey horse. Toby’s identical twin Julian tells detectives about a family legend - if the ghost of Geoffrey points at you it means you will die. Toby’s son Simon blames the ghost for his mother’s death in a riding accident years earlier. He has been struck dumb ever since. The DeQuetteville’s wealthy neighbours, Roundhead descendant Harry Fleetwood and his wife Sasha are being driven mad by the Civil War battles, especially as the DeQuettevilles corrupt history by changing the battle’s outcome in favour of the Cavaliers. When Julian refuses to sell Long Meadow to Sasha, she persuades him to put it up as a wager instead. If the Roundheads win the battle, the Fleetwoods get the land. Then she pays glamorous stable owner Amanda Harding not to hire her horses to the DeQuettevilles.