A weekend gathering at The Hollow, the country estate of the eccentric and scatterbrained Lady Lucy Angkatell, brings together an entangled set of relatives and guests. Among them is Dr John Christow, a driven Harley Street physician, accompanied by his timid, devoted wife Gerda. Also present are Henrietta Savernake, a gifted sculptor and the doctor's cousin and confidante; the gentle, retiring Edward Angkatell; the practical Midge Hardcastle, who works for her living; and the brittle young intellectual David. The arrival of a glamorous film actress from a neighbouring cottage stirs old feelings and sharpens existing tensions. When Christow is found shot beside the swimming pool, the household closes ranks, and a tangle of motives, half-truths, and protective loyalties surfaces. Hercule Poirot, lunching nearby as the Angkatells' guest, stumbles onto a scene so theatrically arranged that he first mistakes it for a charade staged for his benefit. As Inspector Grange pursues the obvious suspect, Poirot senses that the apparent clarity conceals something deliberately constructed. Less a puzzle of timetables than a study of grief, desire, and the masks people wear, the novel lingers on its characters' inner lives as much as on the question of who fired the shot. Each member of the household guards a private wound, and the detective must read the emotional currents beneath a polished country-house surface to understand what really happened by the pool.