Rachel (Emily Blunt) has a serious alcohol dependence. For this reason, her husband Tom (Justin Theroux) left her and married Anna (Rebecca Ferguson). Not long after, the two had the crystallization of love, which made Rachel, who was unable to bear children, heartbroken. Every day, Rachel would take the train into the city. In the picture flashing outside the window, the figure of the beautiful woman Megan (Haley Bennett) attracted Rachel's attention. The young and beautiful Megan lives in a comfortable mansion with her handsome husband Scott (Luke Evans). The two love each other and she has everything Rachel desires but cannot have. However, one day, Rachel was shocked to find that Megan was actually having an affair with a strange man, and it wasn't long before the newspaper published the news of Megan's disappearance.