What an interesting book.
The thing I most enjoy about thrillers, usually, is their sense of control. That's why for a week or two I was all about these locked room thriller movies. I really liked how they set up at the beginning the terms of the story: where you are, the number of characters, the resources you have to work with. Given those constraints, these movies would be fiendish about exploring their conceits to their logical endpoint.
The Girl on the Train is not controlled. It's a book with three first-person present tense narrators. A book that jumps across time, both between and within chapters. It's a book that is to a large extent about things that didn't actually happen. And it's a book where you for most of the book aren't sure what the stakes are or why the characters are involved in it.
This is a book about an alcoholic woman, Rachel, who rides the train back and forth to hide from her flatmate that she's been terminated from her job. She becomes obsessed with a couple she can see from her window: a couple that lives a few doors down from her ex-husband and his new wife. When the woman in the couple goes missing, Rachel forcibly interjects herself into the investigation, talking to the police and to the woman's husband. She makes poor decision after poor decision. And large parts of the narrative are missing or muddled because of her alcoholism.
It's not a book with an antagonist. Rachel is her own antagonist. Every other character continually offers her a way out, and she continually dives back in, making things worse and worse for herself.
But the book also doesn't go in the usual directions. It never really suggests (the obvious twist) that Rachel killed the woman in a blacked out fit. And for most of the book there's no sense of personal danger from the killer. There's no sense at all that there is a killer. There are only about 6 characters in the book, and since two are viewpoint characters, you know immediately there's only a limited number of suspects. In fact most people can work out the killer rather easily, I think.
But that's not where the suspense comes from. It's from this person. Are they going to pull themselves together? Or will they destroy themselves? The self-destruction is almost complete. You come in when it's at about 75%. And as the book proceeds, she gets worse and worse. It's hypnotic, like the movements of a dangerous animal, and there is nothing controlled about it.