Rachel (Emily Blunt) is a divorcée, an alcoholic, and a depressed woman
who is struggling to keep in touch with life. She takes the train for
the city every day and comes back in the evenings with the same train. She always sits in the same place and in order to have the best
view on Megan (Haley Bennett), a girl who lives in a house Rachel passes
by every day and over whom she is unhealthily obsessed.
I will stop there because I would consider anything more than that a
spoiler for the film and if you have yet to read or watch anything about
this film I would recommend to anyone to do as I did and go in
completely blind because I had a blast with this mystery film.