Old, wealthy, and bedridden, Simeon Lee summons his estranged sons and their wives to the family seat at Gorston Hall for Christmas. The reunion is no gesture of warmth: the patriarch delights in needling his children, dangling hints about altering his will and stoking the resentments that have simmered between them for decades. A Spanish granddaughter he has never met and the son of a former business partner arrive to swell the uneasy household. On Christmas Eve, a crash of overturned furniture and a long, dying scream bring the family rushing to Simeon's door, only to find it locked from within. Inside lies the old man with his throat cut, the room drenched in blood and wrecked as though by a struggle, yet no killer to be found. Hercule Poirot, staying nearby, is drawn into an investigation alongside the local chief constable and a dogged superintendent. The puzzle turns on a sealed room, a missing fortune in uncut diamonds, and a family in which nearly everyone had cause to wish the tyrant dead. Sifting old grudges from fresh lies, Poirot weighs each alibi and each inheritance against the character of a man who shaped his children in his own image. The result is a tightly plotted festive whodunit that trades cosy seasonal cheer for something far darker, built on heredity, buried history, and the violence one household can conceal behind a closed door.