In the short story Christmas Adventure, Evelyn Haworth is a house guest at a Christmas house party hosted by Miss Emily Endicott which Poirot also attended. While there, Poirot notices that she is unhappy and she confides in him. Evelyn tells him that originally her family was very wealthy and she was by way of a heiress but then they had lost all their money, and to make things worse, her mother needed an expensive operation. A rich man, Oscar Levering asked her to marry him and offered to take care of her mother. Oscar did indeed pay for her mother's operation and she had recovered. Now she is to marry Oscar some time after Christmas but she does not care for him. She is instead in love with Roger Endicott. She believes he loves her too but he had not said anything earlier and had gone to Australia. Now he has come back but it is too late.
Evelyn's role in the story has no direct parallel in the expanded story The Adventure of the Christmas Pudding but aspects of the character can be found in Sarah Lacey and Diana Middleton.