Hawkins presents her thriller from the perspective of Rachel Watson, a passenger on a commuter train from Ashbury, Buckinghamshire, England, to London and back, day after day. When the train stops at its usual spot before proceeding to the city, Rachel indulges in a daily fantasy, creating lives for a married couple she views from a distance in a Victorian home on the other side of the tracks. She watches for the couple, “Jason and Jess,” every day, imagining what their lives might be like, how much they love each other, how happy they are.

The fantasy is small comfort for a woman who has lost everything: self-confidence, ambition, her beloved home, and her husband, Tom, all exchanged for a rented room a generous friend has offered. Knowing she shouldn’t and fully aware of the potential consequences, Rachel comforts herself with alcohol even on the commute to London, choosing oblivion over reality as the train goes back and forth each day, passing the happy pretend couple and memories too bitter to be endured, her world turned sour with loss and rejection.

Though Rachel’s character dominates the plot, it is a three-pronged narrative. Anna offers an alternative perspective. Anna is now married to Tom after a torrid secret affair. The couple delights in their baby daughter, and Rachel’s home now theirs, the former wife an outsider looking in at the tableau she had wanted for herself. Instead, it’s Anna with Tom: “She’s a cuckoo, laying her eggs in my nest.” Anna is understandably made uncomfortable by the ex who seems unable to let go of her former spouse, habitual drunkenness an excuse for the melodrama of her constant intrusion. Tom treats Rachel kindly, only occasionally losing his temper, though she seems unable to understand that their marriage is over, that he has a new life with Anna and the baby. Then there is Megan, the petite blonde married to Scott Hipwell. Though she tries to be satisfied with her life as a wife, Megan has no sense of direction since the art gallery she managed in town closed for lack of business. She struggles to fill the days until Scott comes home, searching for purpose in spite of the restlessness that plagues her.

As relentless as the clacking wheels of the train on the track, Hawkins drives her characters and her plot forward. Rachel is the fumbling catalyst that crashes into the lives of those she touches, always meaning to help and always failing, succumbing to the need to drink her troubles away, to escape a reality that has spiraled out of control, ever on the precipice of disaster: “I have lost control over everything, even the places in my head.” There are hours--critical--hours Rachel can’t remember, half-formed visions that make no sense. Only Tom is able to calm her down, to explain away her fears, but even Tom has tired of her phone calls and her texts. Anna begs him to report Rachel’s behavior to the police.

It is difficult to maintain any sympathy for the hapless, dysfunctional Rachel. Her behavior is outrageous and intolerable, trying for Tom and the woman from whom she rents a room, abusing even that gesture of good faith. Rachel has imagined a perfect life for the couple she can see from the train, but reality is far from the idyllic scenes spinning in her head. The truth, as it unfolds, is far messier, far more brutal, lies and betrayal undermining relationships begun even with the best of intentions. Out of this accelerating chaos comes a tangled nightmare reverberating with rage, frustration, and a woman’s desire to do the right thing. The result is a final confrontation that will leave you shocked, as sickly fascinated as a fatal wreck along the highway. Brilliantly orchestrated, The Girl on the Train explores human nature at its darkest and most desperate.