Rachel is an alcoholic mess and to avoid her own issues, she fantasizes a perfect life for a couple she see most days when she passes their house on the train. Only no life is perfect and one day she sees something that shocks her and gets her involved in their life and a crime. 
 Overall, I liked the book. That said, my biggest issue was how unlikable every character was. I mean, REALLY unlikable. It certainly kept me from enjoying the book as much as I had hoped.