Tom Barnaby joins the Causton Chamber of Commerce trip to Brighton as he is suspicious of dodgy mayor Hicks' plan to buy coastal land on which to build cottages. Also opposed to the plan is Lady Matilda William, who has received threatening letters, as has the local vicar, oily property developer Hugh Dalgleish, and hotelier Jenny Russell. Lady Matilda is descended from Richard of Guillaume, a ruthless contemporary of William the Conqueror, and believes that her son Richard, last of the line and confined to a wheel chair because of a head injury twenty years past, was the victim of jealousy. In Brighton, Dalgleish was murdered with a sword stolen from Guillaume's tomb, and Hicks is eventually arrested for fraud. Having learnt how Richard came by his accident, Barnaby was convinced that Richard and not the property scam is the cause of another victim being claimed by the sword of Guillaume.
DCI Tom Barnaby heads off to Brighton on a bus tour arranged by the Mayor of Causton, Dave Hicks, and the local Chamber of Commerce. Tom has had his eye on Mayor Hicks for some time and his plan for Causton to buy land on which to build summer camps for underprivileged children has a smell about it. Also on the trip are antiques shop owners Lucy and Trent Terry; hotel owner Jenny Russell; developer Hugh Dalgleish; Rev. Giles Shawcross; and Lady Matilda William, along with her disabled adult son, Richard, and his helper, Marcia Macintyre. Lady Matilda traces her ancestry to 1066 and Guillaume of Normandy. She is very much opposed to the land deal Hicks is proposing in part because Brighton is where her brain-damaged son was injured some 20 years before. When the obnoxious Dalgleish is murdered - decapitated while riding through the house of horrors - Tom works with his cousin, DCI John Barnaby, to solve the crime, It will take a second murder, this time in Causton, for he and DS Jones to identify the killer.
- John Nettles as DCI Tom Barnaby
- Jason Hughes as DS Ben Jones
- Jane Wymark as Joyce Barnaby
- Barry Jackson as Dr. George Bullard
- Kirsty Dillon as DC Gail Stephens
- Lucy Cohu as Jenny Russell
- Rosina Carbone as Lucy Terry
- Darren Tighe as Trent Terry
- Tim McInnerny as Hugh Dalgleish
- Janet Suzman as Lady Matilda William
- Brian Capron as Dave Hicks
- Neil Dudgeon as DCI John Barnaby
- Saskia Reeves as Marcia Macintyre
- Colin Brummage as Richard William
- Mark Gatiss as Rev Giles Shawcross
- Julia Watson as Christine Wakely
- James Greene as Douglas Wakely
- Billy Geraghty as Bill Russell
- Robin Soans as Perkins
- Jamie Langlands as Male On Ghost Train (uncredited)
- Chris Wilson as Police Officer (uncredited)
- This episode marks the debut of Neil Dudgeon as DCI John Barnaby.
- Brian Capron returns in his role as Mayor Dave Hick, previously appearing in Shot at Dawn in which Barnaby investigated a case where his whole family was implicated.
The following actors and actresses who appeared in this episode have also appeared in the following episodes