One of the most disturbing Stephen King novels is 'Pet Sematary'. The idea of a burial ground that brings the dead back in a twisted way is truly creepy. The consequences that unfold as characters use it are filled with horror and despair.
'The Shining' can be considered very disturbing. A family isolated in a haunted hotel, and the slow descent of the father into madness. The visions, the ghosts, and the sense of claustrophobia within the hotel walls make it a nerve - wracking read. The idea that the hotel has a life of its own and can manipulate those inside is truly chilling.