The Cabin at the End of the World by Paul Tremblay. Was the basis for Knock at the Cabin, book is (unsurprisingly) SO much better and past a certain point VERY different from the film. Propulsive, devastating, etc.
I see it’s already been recommended so I will also throw my hat in the ring & say you should read Bath Haus 🙏🏻 just be prepared to get comfortable being uncomfortable