Pet Semetary by Stephen King is a frightening book and probably my favorite Stephen King book at the moment. The way King writes his characters and the town they live in, gives me a feeling of fear. A fear of the highway and large semi trucks driving at high speeds. A fear of some old evil entity existing somewhere in the world.
Confessions by Kanae Minato. The first couple chapters had me hooked and it was enough to stick around to see who did it. I would watch the film if I ever had the chance. It's about a teacher whose kid is killed and she is interrogating the classroom on who did it.
Parasite Eve by Hideaki Sena. The game based off the book. It has a dark tone to it, starting at the beginning. You're then taken on a journey. Don't expect a 1:1 of the game here though.
Genocidal Organ by Project Itoh is another disturbing book. Which is probably why I enjoyed it so much. It's very graphic and you feel the pain of war/destruction caused by war. It's been a while since I read it. I also like The Hobbit.