THE GIRL ON THE TRAIN – Novel by Paula Hawkins

Maybe, often you happened to observe people from a window, imagining their lives. Rachel – the protagonist of this novel – whose life (apparently perfect), has recently been shattered, she observes two people every morning, for a few minutes (from a train window), and that couple is become for her an obsession. Those two people, living to her old house. But what happens when, suddenly, one of those two people disappear?

http://www.amazon.it/The-Girl-Train-Paula-Hawkins/dp/1594633665