Plot Summary:With Ben Jones promoted to inspector in Brighton, Barnaby is joined by new sergeant Charlie Nelson, to investigate the murder of Conor Bridgeman during a ghost hunt at a house in Morton Shallows. Though married, Conor was using the hunt as a cover to meet his girlfriend, had fallen out with the impoverished owner of the house, Simon Fergus-Johnson, who had refused to sell it to him and was disliked by local historian Brendan Pierce, whose daughter Bridgeman had seduced. Whilst the murderer is clearly human, mysterious pamphlets circulate the village, warning not to disturb the spirits, who will wreak revenge, and a second ghost hunt leads to another murder, that of pub landlord Ross Clymer, lover of Simon's wife and enemy of army deserter Ollie Tabori, the former boyfriend of Simon's put upon sister Valerie. Ultimately Barnaby discovers the reasons for the slayings are family based, using for their cover the superstitions surrounding the Christmas hauntings.