An urgent letter brings Hercule Poirot and Captain Hastings across the Channel to a quiet seaside town in northern France, where a wealthy man has begged for protection against an unnamed threat. They arrive too late: the millionaire lies dead in a freshly dug grave beside an unfinished golf course, stabbed in the back, while his wife is discovered bound and gagged in the villa. The local magistrate and the celebrated Sûreté detective Giraud each pursue the case in their own fashion, and Poirot soon finds himself measured against a younger rival who trusts cigarette ends, footprints, and the new science of detection over the workings of the human mind. As Poirot sifts the household's tangled loyalties, he uncovers an old scandal, a buried identity, and motives rooted in jealousy, money, and love. Hastings, meanwhile, is distracted by a spirited young woman he met on the train, an acquaintance that complicates his judgement at every turn. The investigation widens to take in the victim's troubled son, the neighbouring family, and a crime whose shape echoes one from decades past. Poirot insists that order, method, and psychology will reveal the truth where physical clues only mislead. Set against polite drawing rooms and coastal lanes, the story turns on the gap between what people show and what they conceal, building toward a resolution that asks who truly stood to gain from a death dressed up to look like something else.