If you are looking for literary suspense and something quite different than the usual psychological suspense novel consider::
The Magus by John Fowles
From Goodreads:
“At the center of The Magus is Nicholas Urfe, a young Englishman who accepts a teaching position on a remote Greek island, where he befriends a local millionaire. The friendship soon evolves into a deadly game, in which reality and fantasy are deliberately manipulated, and Nicholas finds that he must fight not only for his sanity but for his very survival.”
https://www.goodreads.com/book/show/16286.The_Magus