Gone Girl, which I very much enjoyed. I had read the book a year ago, and although I liked it, I wasn't crazy about it.
The movie, however, is kind of excellent. It doesn't change anything, following the book closely. It's a very good story (I don't want to give anything away), and one of the things that makes the movie more gripping is the way the music and sound effects added tension and suspense to the scenes. Although the book was a total page turner, I never felt frightened, as I did in the movie. The acting was also very good, and I really enjoyed Ben Affleck as Nick Dunne -- that important character never really jumped off the page for me. The actress who played Amy was impeccable and creepy, really good.