In the afterword, Hawkins thanks all the commuters on her London train. My guess is that she's thanking them because she noticed how few folks actually look out the window, and it got her thinking about what might happen if they actually did look out the window...
This is not the best book I've ever read. It was entertaining in a Dan Brown sort of way, replete with thrilling chapter endings and some large leaps in logic for the purpose of the plot. For instance, there were far, far, far too many instances of Rachel happening to end up near her ex's house, which became both obvious and tedious towards the end.
The book strums a single note throughout - that of the ineffable sadness of a life without children and how that can lead you to do all sorts of awful things including falling into alcoholism - but also seems to be plinking the piano on the theme of men being physically stronger than women and what that can imply. For those of us who don't have kids, that first note can get boring quickly, while the second note seems overwrought. Especially in light of how the book wraps itself up. What I'd really like to bitch about I cannot do without giving away the entire conclusion, but anyone finishing it will wonder why we were led to believe a certain marital bliss when it was apparently not true.
I doubt I'll watch the movie, even though I find Emily Blunt a surprisingly forthright actor with an uncomplicated style. Which would be quite interesting to watch in a portrayal of an alcoholic.