“We Have Always Lived in the Castle” by Shirley Jackson

This is a good but gruesome psychological study of 2 sisters who are obviously mentally unsound. The story is told from the point of view of the younger sister who is frighteningly insane. It is not a surprise at the end to learn that it was the younger sister, not the older... as was supposed, that murdered her family with arsenic in the sugar. The neighbouring townspeople as well, are an unpleasant study in ugly psychological behaviour.