Kitty Winter was a mistress of Baron Adelbert Gruner. The baron destroyed Kitty's life and she wants revenge. She attempted to help Sherlock Holmes end the Baron's engagement to Violet de Merville telling his fiancée of his sordid past, but Violet refused to believe her. Kitty also tells Holmes that the Baron "collects women" and chronicles his conquests in a book which he keeps in his study.