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. 

They begin their search, but then Detective Sloan receives a call that one of the legatees has died following an attack of food poisoning. Now detectives Sloan and Crosby must determine whether the deceased merely ingested a noxious substance by accident or if the legatees are being picked off one by one.