At the prologue, veteran lawyer Mr Treves remarked that investigations at a murder oft looked at the murder as the starting point when oft murder was the end and that the real story began long before.
And so Agatha Christie introduced many disparate threads in the beginning that appeared to have absolutely no relationship whatsoever with each other - Inspector Battle's daughter getting into trouble in school, a failed suicide of a man let down by the world when all he did was to be honest, a young man getting his wife and ex-wife down to his adopted country seat home at Gull's Point.
The deaths did not come in until about half the book, the first person to make the exit being Mr Treve himself. Next was the elderly widow Lady Tressilian, matron of Gull's Point.
Rounding up the usual suspects, we have Neville Strange, young, rich, semi-pro sportsman; his second wife Kay, a glamorous hothead from the Riviera; his divorced first wife Audrey, a complete contrast in character to Kay, stately, willowy and dignified; Thomas Royde, family friend on home visit from Malaya, devoted to Audrey for years; Edward Latimer, friend to and similarly devoted to Kay; Mary Adlin, Lady Tressilian's companion and manager of the household; plus an assortment of domestic help.
Did Kay kill Lady Tresslian, thinking she would be the beneficiary to the legacy as wife of Neville Strange? Especially when Neville declared he intended to divorce her to get Audrey back.
Was Audrey the culprit, knowing she was the actual beneficiacry, being the wife of Neville when the will was drawn up, mentioned in name specifically?
Or was it Neville, to thwart Lady Tresillian's objections to his divorcing Kay to get Audrey?