Four strangers arrive at the solicitors' office of Puckle, Puckle, and Nunnery. They have never met, and have no idea why they have been invited. But they – along with a missing man – are descendants of the late Algernon George Culver Mayton, the inventor of ‘Mayton's Marvellous Mixture’ and each entitled to a portion of the Mayton Fortune. But before they can split the money, the missing man must be found. Two months later, Detectives Sloan and Crosby receive a call that one of the legatees has died following an attack of food poisoning. Did the deceased merely ingest a noxious substance by accident, or are the legatees being picked off one-by-one?