Barnaby decides to join Causton's annual trip to Brighton, suspicious about plans by Causton mayor Dave Hicks to buy up coastal land for holiday chalets. Also against the proposal is Lady Matilda William, who owns most of Midsomer Parva.


Rev Giles Shawcross asks Barnaby to investigate threatening letters sent to Lady Matilda, property developer Hugh Dalgleish, voluptuous hotelier Jenny Russell and the vicar himself. Jones, meanwhile, receives a complaint from antique dealers Trent and Lucy Terry, who claim Dalgleish is stopping their right to roam the countryside.


Lady Matilda's husband was descended from Sir Richard Guillaume, a Frenchman who killed many people during the Norman Conquest. She believes her son Richard is the victim of a revenge attack against his ancestor. Twenty years ago he was mugged and is now brain damaged and cared for by Marcia - but the Guillaume line will end.


Hicks is worried about Barnaby's presence on the trip and phones the mayoress of Brighton, Christine Wakely. The detective is met by his cousin, DCI John Barnaby of Brighton CID, who tells him the land wanted by Hicks is prone to flooding from the sea.


The Terrys persuade Christine's elderly father Douglas to part with some historical swords, under the guise of an insurance valuation. Some villagers go to the funfair - but when Dalgleish takes a ride on the ghost train he comes out of the tunnel beheaded.


Back in Midsomer, police raid the Terrys' house and find the missing swords. But they are too blunt to be the murder weapon and Trent claims Hicks put them up to it. John Barnaby discovers Christine proposes to build flood defences which would make Hicks' land rocket in value, while Dalgleish lent Hicks £100,000 to bribe councillors to agree.


Jenny is beheaded in her bed, and Barnaby questions Giles about his relationship with Richard. He confesses they were lovers whilst at Oxford and met in Brighton where Giles accidentally crippled Richard during a row. He believes God brought him to Midsomer to atone for his sins.


Hicks is arrested while Barnaby tells Lady Matilda the truth about Giles. He realises there could be a connection between the threatening letters, Dalgleish's greedy desire for land and Lady Matilda's desperate longing to preserve the Guillaume family line. But who is prepared to kill to protect Richard?