Shutter Island has a really intriguing premise: a severely disturbed psychiatric patient has excaped from a high-security island mental institution/prison requiring US Marshals to investigate. It's set in the 1950s so the setting invites a little Maltese Falcon-esque noir into the mind's eye. When Teddy and Chuck (the Marshals) start to investigate the goings-on at Shutter Island things start to get a little wierd. And that's an understatement.
Dennis Lehane has a fantastic gift for descriptions and he sets the mood so, so well. Teddy has fantatstical dreams and they are so vividly described, adding to the heightened suspense (which was already at a fever pitch due to the hurricaine).
Unfortunately, I had the plot twist figured out by the time the hurricaine passed the island. While Lehane's description kept me going I was a little disappointed when the denoument proved me right. I'm a huge Sherlock Holmes fan and I love the "aha!" moments in those stories, I'm never disappointed to find out I'm right or wrong. With Shutter Island I just didn't have an "aha" moment; the revelation just felt old-hat. Also, I thought Lehane wimped on the plot in the last chapter.
Shutter Island was fun to read, a nice diversion, and I wanted to get the book read before I watched the movie.