Although the credits describe the original story, by Osbert Sitwell, as a novel, it is only 35 pages long, not even long enough to be a novella. It is a short story, one of several in a collection called "A Place of One's Own and Other Stories."
Annette is dying because she is possessed by the spirit of a woman who lived in the house. People say that the house is evil and should be torn down. Everyone helplessly watches her die. It is never explained why, if Annette's illness is caused by the house, she is not taken away from it.