The Hound of the Baskervilles (1959 movie)
Rather than being Stapleton's daughter, Miss Stapleton is Stapleton's wife in the novel and is playing the part of his sister. She does not hate Sir Henry, as she does in the film, and is a far more sympathetic character in both the novel and in nearly all the other film versions of the story. Cecil in the novel is named Beryl and is an unwilling participant. In the film, she is much more sinister. Miss Stapleton survives in the novel, whereas in the film she drowns in the Grimpen Mire.