The Dark Rider

S15, E1: Barnaby and Jones investigate when the appearance of a headless horseman at Quitewell Hall foreshadows a number of deaths among an aristocratic family called the DeQuettevilles. Meanwhile, the family stage a Civil War re-enactment with their hostile neighbours and relive historic battles. Can the detectives uncover the truth about the DeQuettevilles and the ghostly rider in order to prevent more murders?