Honestly, I would give this three and a half. As others said, I couldn't put it down and the writing was quite good. However, there was a building that occurred over the course of the book that made a promise, one that I felt was unfulfilled in the end. I'm not sure if I wanted to be left with more mystery, or if I just felt the way things came to a close was ultimately unsatisfying. I give it four for atmosphere and keeping me up late at night, which is all too rare.