The Girl on the Train recap

Rachel, a divorced alcoholic prone to blackouts, rides the same commuter train daily and fixates on a couple she watches from the window, whom she imagines to be perfectly happy. When the woman, Megan, vanishes, Rachel inserts herself into the investigation, convinced she saw something important on a night she was too drunk to remember. Told through the unreliable voices of Rachel, Megan, and Anna, the new wife of Rachel's ex-husband Tom, the book gradually reveals that Megan has been murdered. The killer is Tom: he had been having an affair with Megan and killed her when she told him she was pregnant, striking her down and hiding her body. Tom is also a practiced liar who spent years gaslighting Rachel, convincing her that her drunken blackouts had made her do shameful things she never actually did. As Rachel recovers the truth of what she witnessed, she and Anna together confront Tom, and in the struggle Rachel kills him to defend herself, freeing both women from him.

Rachel Watson is a divorced woman whose drinking has cost her marriage, her job, and much of her stability. Twice a day she takes the commuter train past her old street, where her ex-husband Tom now lives with his new wife and baby. From the window she also watches another couple a few doors down, strangers she has never met but whose seemingly perfect life she has built into a comforting fantasy. When the woman she has been watching, Megan, goes missing, Rachel becomes convinced that something she glimpsed from the train, on a night blurred by alcohol, matters to the case. Unable to leave it alone, and unreliable even to herself, she begins inserting herself into the lives of the people involved, setting off a chain of events that will force her to confront both the mystery of Megan's disappearance and the truth about her own past.

The mystery resolves on Rachel's ex-husband, Tom. Megan had been employed by Tom and Anna and had begun an affair with Tom; when she told him she was pregnant, he killed her in an underpass near the tracks and concealed her body in nearby woods. The night of the murder, Rachel had been drunk and near the scene, and Tom had exploited her blackouts for years, feeding her false memories so she blamed herself for outbursts and failures that were really his doing, part of a long pattern of manipulation that had helped destroy her. As Rachel pieces together what she actually saw and understands that Tom is the murderer and the source of her ruin, she goes to warn Anna. Tom turns violent, and in the confrontation at the house Rachel stabs him with a corkscrew in self-defense; Anna, now aware of the truth about her husband, ensures he is dead. Megan's killing is solved, Tom's lies are exposed, and Rachel begins to reclaim her life with a clearer sense of what was done to her and what she is capable of surviving.