In November 1929, Violet Sydney died from what was subsequently shown to be arsenic poisoning. In fact, two other members of her family had died in the previous year, her daughter Vera and her son-in-law Edmund Duff. With those bodies subsequently exhumed, they too were found to have been poisoned. As the family matriarch, Violet was very demanding of her three children and brooked no disagreement from them. There were several suspects in the case. Edmund was married to Violet's eldest daughter Grace; a son, Thomas, was desperate to return to the USA with his American wife; Dr. Jackson, who treated all three of the deceased, was quite taken with Grace and may have had a hand in the deaths. Finally, there was also the cook who prepared the soup that killed Vera. Although the case of the Croydon poisonings was never solved, Julian Fellowes hosts this dramatic re-creation of the events and offers his own views on the likely murderer.