Danby Hall is the only home Lady Cecilia Bates has ever known, but when an agricultural depression sweeps the region in 1912, the family's possession of the hall is suddenly in peril. The Earl and Countess of Avebury are determined that Cecilia's brother, Patrick, will win imperious American millionaire Annabel Clarke's hand in marriage—and her fortune along with it. The Bates family and its staff arrange a grand house party upon the heiress's arrival, but when a guest dies after sipping from a glass meant for Annabel, it's clear the Bates have a scandal on their hands. In this series debut, Cecilia sets out to find the culprit, with help from Annabel's maid, Jane, and her curiously intelligent cat, Jack.