The first of the murders in Dead Man’s Folly occurs at one of those typically English affairs, the village fête which is held on a Saturday afternoon in summer in the grounds of the local manor house. At Nasse House, in Nassecombe, on the river Helm in Devon, that celebrated detective-story writer Mrs Ariadne Oliver agrees to take part in the fête and to invent a Murder Hunt, based on the Treasure Hunt game. During the fête, a local girl, cast as ‘the body’ in the Murder Hunt, is found dead.

The local names are fictitious. For Nasse House and the river Helm, read Greenway House and the Dart, for Agatha Christie has based this ‘big white Georgian house looking out over the river’ on the house on the upper reaches of the Dart which she and Max Mallowan had purchased in 1939 and had lived in since the end of the war. (The author’s daughter and son-in-law now occupy it.) She has even made use of Greenway House’s boathouse: ‘It jutted out on to the river and was a picturesque thatched affair.’10 That was where Mrs Oliver intended ‘the body’ to be discovered, and that is where, despite the presence of Hercule Poirot at the fête, it is discovered.

Poirot was summoned by Mrs Oliver, who had vague forbodings that something might go wrong, for she had been staying at Nasse House for a day or two before the fête, and sensed that the atmosphere was somehow wrong. Dead Man’s Folly begins with Mrs Oliver’s phone call to Poirot, whose telephone number, trivia collectors will want to note, as TRAfalgar 8137. ‘I don’t know if you’ll remember me,’ Mrs Oliver says to Poirot, but of course he does. They first met twenty years earlier (see Cards on the Table, 1936) and, again, only four years earlier when Poirot investigated the death of Mrs McGinty (Mrs McGinty’s Dead, 1952).

And so Poirot takes a train to Devon, and to the riverside house not far from Dartmoor. The moor, one of Agatha Christie’s favourite places where in old age she still loved to picnic with family and friends, does not intrude into the narrative but is palpably there in the background as it is in more than one other Christie novel. (The chauffeur who conveys Poirot from the railway station at Nassecombe to Nasse House attempts to draw the great detective’s attention to the beauties of the scene – ‘The River Helm, sir, with Dartmoor in the distance’ – and Poirot makes the proper appreciative noises although he has very little interest in nature and scenery.)