Shutter Island, by Dennis Lehane
This is the type of book that totally screws with your mind. If you don't like such books, steer clear.
I didn't know much about it when I started it (except that it was a movie and by the author of Mystic River), so I was not aware that this would be the case.
I like Lehane's writing style and the book drew me in immediately.
When I finished the book, I wasn't absolutely positive what was true in the end. I suppose that's because I don't usually read these noir types of books and am not the sort of reader who tries to figure things out and look for clues along the way.
I'm intrigued enough by Lehane's writing and creativity to try another one of his. If you like psychological thrillers, you will probably like this one. Creepy and haunting!