Charles Hayward returns to post-war England hoping to marry Sophia Leonides, the woman he fell for during his wartime service abroad. Before they can build a life together, word arrives that Sophia's grandfather, the wealthy patriarch Aristide Leonides, has died of an apparent poisoning. Three generations of the family share a single rambling house called Three Gables, bound together by the old man's money and his outsized personality, and every one of them had reason to want him gone. Sophia refuses to marry Charles until the truth is known, fearing that an unsolved death will poison whatever they try to build. Because Charles's father is a senior figure at Scotland Yard, Charles is drawn into the investigation alongside the police, moving through the household as both suitor and observer. The widow decades younger than her husband, the resentful sons, the actress daughter-in-law forever performing, the children, the tutor, and the sharp-tongued aunt who runs the house all guard their own secrets. As the inquiry tightens, suspicion shifts from one relative to the next, and the closed circle of the family begins to fracture. Told entirely through Charles's narration, the story studies how a single dominating man can warp the people who depend on him, and how the search for a killer forces each member of the family to be seen plainly at last. The answer, when it comes, reshapes everything that came before it.