Shirley Jackson was always quite effective, in her own way, in portraying the inner life of the psychically disturbed. This tale in the tradition of "The Fall of the House of Usher" is a signal bit of American Gothic, with a proto-feminist twist.
Two sisters, one quite mad, and an old uncle have sequestered themselves on the family estate after one of the sisters has done off the rest of the (apparently) unpleasant family with arsenic. They live in a reasonably comfortable stasis until the arrival of a male cousin whose motives seem torn between freeing the older sister into society and plundering the family's hidden weath. His presence breeds resentment and threatens the delicate balance, until a crisis is reached on one dreadful, apocalyptic night when the house burns and is trashed by vengeful villagers right out of an old Frankenstein movie. Jackson does not end the novel there, but instead shows how a new normalcy is built in the chaos by the beleagured sisters. This is a popular novel that is, at the same time, deserving of its reputation as a modern classic.
Note: I have the classic 1963 Popular Library paperback edition of this book (shown above), however, the link below is to the recent Penguin Classics Deluxe edition, with the wonderfully weird cover illustration by Thomas Ott.