The Girl on the Train, by Paula Hawkins, 336 pages
Have you ever read one of those books that everyone else is reading and talking about, and when you finish it, you're like: "So... why is this popular?" This was like that for me. Rachel takes the train every day, to and from London, and she always sees a couple at one of the train stops. She's created a whole fantasy surrounding them and their lives, and when the woman goes missing, she finds herself drawn to help solve the mystery. Personally, I found just about every character to be unlikable and annoying, and when the "mystery" is solved, I could not have cared less.