I saw Great Granny Webster by Caroline Blackwood in a list of classics that someone or other wanted the BBC to make for television. Actually, it was a suggestion in the comments, and after suggesting it the commenter remarked that unfortunately it was unfilmable. The library had it, and so I read it. It's a dark little gem.
I don't know about it being filmable or not. It seems possible to me. But I think what the commenter meant was that it's relentlessly verbal--the whole effect of the book comes from the voice of the narrator. She gives the illusion of being completely passive. She takes no actions. The book has chapters about three of the narrator's relatives: her great grandmother, her aunt, and her grandmother. In the first two cases she spends time in their presence without saying a word or doing anything, and in the third case, she is supposedly relating a story from a family friend--I say supposedly because there is not a word in this book that is not conveyed in her own voice, which is bitter and very snarky. It's a neat trick, actually. At first she seems passive, but she's actually in complete control of the tiny, hopeless, airless world of this novel. If the other characters appear horrible--and most of them do--we can't forget that she's speaking through their mouths for them. There is awful pain in the narrator's family, but it seems like she's blind to it. Another book could be written that features exactly the same story, and with a different narrator it would be a truly sympathetic tragedy instead of a dark comedy. Is that just the definition of dark comedy though?