The TV Show "Downtown Abby" is based on the story of a Rothschild Heiress.

https://www.tatler.com/article/downton-abbey-real-life-inspiration

It is said that Lady Cora was the first character to come to life for Fellowes and that she is based on Lady Almina, the 5th Countess of Carnarvon. Daughter of banking giant Alfred de Rothschild, the American heiress’s vast dowry helped save Highclere Castle

In 1895 alone, nine American girls, including Consuelo Vanderbilt Spencer-Churchill, Frances Ellen Work La Roche, Millicent Rogers and Gertrude Vanderbilt Whitney, all married into the British aristocracy. Reading between the lines, we can see that Fellowes was also heavily influenced by Lady Almina’s daughter-in-law, Lady Catherine, and Lady Mary of Kedleston.

In the fictional series, Lady Cora is brought to London in 1888 by her socially ambitious mother. During the season, she meets Robert Crawley, the future Earl of Grantham. Much to Robert's mother's disapproval, the two become engaged, and marry in 1890. Much like the real heiresses of the time, Cora's dowry is tied to the family estate to prevent it from going bankrupt as part of their marriage contract.

Back to reality in 1890, the present Lord Carnarvon’s great grandfather inherited Highclere Castle. Land rich and cash poor, the 5th Earl ran up huge debts; the only solution was for him to marry the teenage heiress, Lady Almina Wombell. As part of their marriage settlement, de Rothschild paid £2,000,000 to cover the Earl’s debts, as well as providing Almina with a dowry of £8,000,000. Almina’s family wealth insured that the flag continued to fly over Highclere and her influence is still felt today.

As the Earl who married the Rothschild daughter, Almina, his death began the myth of the mummy's curse.

He inherited the Earldom of Carnarvon in April 1923 on the death of his father – who had funded archaeologist Howard Carter's search for the tomb of Tutankhamun. The new earl's view of the suggested 'Curse of Tutankhamun' was that "however sceptical I might have been, I could not dismiss the matter out of hand",[5] claiming that the moment his father died on 5 April in Egypt, the family dog howled and died a sympathetic death at Highclere Castle, the family seat.[6] On becoming Earl, he took on responsibility for the upkeep of Highclere Castle and its 4,000 acre estate.[3] His mother remarried only eight months after the death of her first husband.

Almina (Rothschild) wasted no time in remarrying after the "mummy's curse" killed the 5th earl off and the Downtown Abby estate became the Rothschild's.

What happens when you marry into the Rothschild family to pay your debts:

In early 1923, British archaeologist Howard Carter and his financier friend George Herbert, Lord Carnarvon, ceremoniously opened the long-obscured burial chamber of the boy pharaoh Tutankhamen in Egypt’s Valley of the Kings. Two months later, Carnarvon was dead, killed by blood poisoning from an infected mosquito bite on his cheek.

Newspapers speculated that he was the victim of the “mummy’s curse” or “curse of the Pharaohs,” which supposedly promised death to anyone who disturbed the rest of the kings and queens buried in the valley.