Rachel Watson (Emily Blunt) has self-imploded following an acrimonious divorce from her cheating husband, Tom (Justin Theroux).
When she wakes from her drunken stupors, Rachel has alarming gaps in her memory and, on one occasion, she is covered in bruises and blood. As a result of her intoxication, Rachel loses her job at a PR firm, which she conceals from her roommate Cathy (Laura Prepon) by taking her usual train each morning and sitting in the park with a bottle of spirits.
The journey takes her past her old house where Tom is now happily settled with his mistress Anna (Rebecca Ferguson) and their baby.
The tracks also pass by the residence of neighbours Scott (Luke Evans) and Megan Hipwell (Haley Bennett), and Rachel fantasizes about the couple’s seemingly perfect relationship.
One morning, Rachel stares bleary-eyed out of the train window and glimpses Megan in a clinch with another man. Megan subsequently vanishes and Detective Sergeant Riley (Allison Janney) becomes interested in Rachel’s hazy recollection, especially since the drunkard has no alibi for the hours leading up to Megan’s disappearance.
Perhaps psychiatrist Dr Kamal Abdic (Edgar Ramirez) can help Rachel to unlock her subconscious. She will soon realise that some memories are best forgotten.
The Girl On The Train is a smart psychological potboiler anchored by a strong performance from Blunt as a self-destructive woman, who is figuratively going off the rails in her darkest hour.