The Woman in the Window by A. J. Finn
I love nothing more than a good thriller, and this one kept me captivated from the start. Not only was it a real page-turner with plenty of twists and turns, but you really become attached to the main character Anna and want to help her decipher what's real and what's not. All-in-all it's a great beach read that you won't be able to put down. Plus, the movie version starring Amy Adams and Julianne Moore is being released later this year, so if you haven't read this yet, now is the perfect time.