The Sword of Guillaume

The Causton Chamber of Commerce goes on a day trip to Brighton, and it ends about as badly as a chamber of commerce outing can end. The occasion is a ceremony and the transport is a bus, and somewhere along the route a killer starts taking heads with an ancient sword. In Causton and in Brighton alike, members of the party are found decapitated, and the murders have a theatrical quality that sits oddly with the seaside postcards. The case sprawls across two towns, which means twice the doorsteps and twice the alibis, and the body count keeps the whole coach party looking nervously at one another.

Tom Barnaby does not have to face this one alone. His cousin John, also a DCI, works the case with him, and the two Barnabys make a decent double act; it is the closest the series comes to a family reunion with a body count. Ben Jones is in there too, with DC Gail Stephens; Joyce holds the home front, and Dr Bullard counts the bodies. The travellers themselves are the ones at risk: Jenny Russell, Lucy and Trent Terry, Hugh Dalgleish and Lady Matilda William, all of them suddenly aware that the person next to them on the bus might be carrying a very old blade.

Michael Aitkens wrote the script with Caroline Graham, and Renny Rye directed. John Nettles and Jason Hughes lead the regulars, with Tim McInnerny and Janet Suzman lending the guest list proper weight alongside Lucy Cohu, Rosina Carbone and Darren Tighe.

But a serial killer with a sword is not a subtle business, and the episode knows it. The pleasure is in watching two Barnabys grind through village gossip while a weapon from another century does the real talking. It is daft enough to get away with, and exactly what fans of the show are after.