A year before Paula Hawkins’ debut novel hit the stands, Universal secured the rights to what was sure to be the next Gone Girl — a mystery thriller about three women and the disappearance that ties them together. Sure enough, The Girl on the Train became a bestseller, and the film adaptation, which stars Emily Blunt, Haley Bennett, Rebecca Ferguson and Justin Theroux, hits theaters this weekend. As expected, there are some differences between Hawkins’ book and Tate Taylor’s film, but just how many changes were made from page to screen — and how big are they?

Hawkins’ novel was already a massive success before it was released, with the studio banking on attracting fans of Gone Girl. Aside from being a mystery thriller with a flawed female protagonist and using different character perspectives (three to Gone Girl’s two) for each chapter, the stories aren’t really comparable. Hawkins’ book is a bit underwhelming, and squanders compelling themes of chemical dependency, co-dependency and abuse on a narrative gimmick that never quite pays off.

It definitely pays off a bit more in Tate Taylor’s film adaptation, which centers on Rachel, a divorced alcoholic who becomes obsessed with the seemingly perfect husband and wife whom she observes from the train every day. The same night that Rachel stumbles off the train to drunkenly confront her ex, the wife goes missing, leading Rachel to question her possible involvement. Depending on how you feel about Hawkins’ novel, you may find that some of the changes improved the story for the film, while others doubled down on existing flaws.

This post contains SPOILERS for the book and film versions of The Girl on the Train. You have been warned.

1. Setting

This is the first, most obvious change. Hawkins’ novel takes place in London, and although it features a cast that includes Swedish actress Rebecca Ferguson and Welsh actor Luke Evans, only Blunt gets to retain her natural British accent in the film’s New York setting. Despite the change in location, the Westchester area of New York looks every bit as upper-class-suburban as described in the novel.

2. Rachel is not frumpy — at all

The film version of Rachel (Blunt) doesn’t look much different from the actress who plays her. Her eyeliner is a bit cakey and her eyes are bloodshot from day-drinking through her lonely existence, but mostly she just looks like Blunt after a long night and a tough breakup. As described by Hawkins, the book version of Rachel has put on a bit of weight due to her drinking and depression, and often appears disheveled with stains on her clothes. As it stands, Movie Rachel is hardly the portrait of alcoholism.

3. Rachel draws

I’ll give Taylor and screenwriter Erin Cressida Wilson this much: At least they gave Rachel a hobby. Book Rachel is a total mess who lost her PR job and has no interests outside of drinking, stalking her ex and his new wife, and obsessing over Megan (Bennett) and Scott Hipwell (Evans) during her commutes in and out of the city, where she pretends to go to work. Movie Rachel is more of the same, but here she has something she’s passionate about beyond being a collection of antiquated female stereotypes. It also gives her a way to connect with Megan…

Universal

4. Megan’s affair with Abdic isn’t a big reveal

Taylor offers some visual clues early on for the backstory of Megan, whose past is largely obscured for most of the book. Unlike the source material, Megan begins seeing Dr. Kamal Abdic (Edgar Ramirez) right away, not at the behest of her husband, and her affair with Abdic begins immediately. Her brother’s death, which affected Megan so deeply in the book, is barely mentioned.

5. But her history is still a secret

Although the film rushes to get Megan into therapy to discuss her issues, her past relationship with the mysterious Mac and the horrific death of their baby, Libby, is reserved for the third act. In the novel, her tragic past becomes public knowledge and is sensationalized by the media; in the film, Abdic is the only one who knows about Mac and Libby.

6. The format is mostly the same

Like the book, The Girl on the Train uses a slightly non-linear format, dividing its narrative among the perspectives of Rachel, Megan and Anna (Rebecca Ferguson), with each segment peeling back an additional layer of the story. For book readers, the mystery may not be as thrilling, but Taylor’s film definitely handles the shifts between characters with a bit more grace. His consolidation of their individual stories makes the film more plot-driven, but loses a lot of the character-building and nuance.

7. Rachel interacts with more people

Her roommate Cathy (Laura Prepon) is much kinder and more understanding than in the book, where she’s just an old college acquaintance with no particular affection for Rachel. The film version also sees Rachel becoming drinking buddies with a woman at a bar (for one night, at least), and we actually see her attending AA (much earlier than she does in the book) — these scenes basically repurpose the novel’s lengthy inner monologues and allow us to get to know Rachel a bit better through actions instead of words.

Universal

8. Megan is a Manic Pixie Dead Girl

This is an occasionally annoying trope in mystery thrillers: The missing or dead girl is depicted as some near-mythical, elusive and hyper-sexualized creature; she is the ultimate object of desire because you can’t ever know or have her — she’s gone. From Laura Palmer on Twin Peaks to The Killing’s Rosie Larsen and, more recently, The Night Of’s Andrea Cornish, these deceased and disappeared women are idealized in unhealthy ways, and the ultimate tragedy is that they aren’t around to defend themselves. Part of what makes Gone Girl so effective is its clever, unflinching subversion of this specific expectation.

It’s normal to romanticize the dead, but The Girl on the Train makes a familiar and fatal mistake by explicitly sexualizing Megan to such a degree that she’s not even a human being. This is especially disappointing from screenwriter Erin Cressida Wilson, whose past credits include Secretary, an unconventional BDSM rom-com that is incredibly perceptive about mental health and gender dynamics in sex and relationships.

9. Cathy doesn’t have a boyfriend

Hawkins’ book has a whole minor plot involving Cathy’s boyfriend, Damien, with the two of them constantly judging Rachel for her behavior while also setting an example of the life she once had. Cathy often comes home to find Rachel’s drunken messes (vomit, wine bottles, et al.) and acts like a nagging den mother, eventually telling Rachel to move out. In the film, Cathy doesn’t have a boyfriend, nor does she seem to exist outside of her scenes with Rachel.

10. Tom is barely a character

Tom (Justin Theroux) had a much bigger role in the book, in which he shares an intimate moment with Rachel and offers her some cash. It takes him much longer to become fed up with her incessant late-night phone calls and drunk texts. Movie Tom isn’t around much, which makes the big climactic reveal that he had an affair with Megan and killed her far less effective. Like who even cares about this guy? Oh, and when we find out that Tom lied to Rachel about her drunk behaviors, it’s less impactful because it’s all muddled with stuff about Megan.

Universal

11. Anna is even less of a character

As our own Erin Whitney perfectly describes it, Rebecca Ferguson isn’t even a person in this movie: She’s a corpse. The book version of Anna has little-to-no agency and mostly serves as a vague parable about how the other woman will become the wronged wife, or something. She’s bizarrely passive, especially when Tom attacks and tries to kill Rachel during the climax. The film version of Anna is even worse: As Tom attacks Rachel, Anna just looks on silently from an upstairs window. She is the human equivalent of a shrug.

12. Megan’s surprise pregnancy

In Hawkins’ novel, the only person Megan tells about her pregnancy is Tom, when he picks her up in the tunnel on that fateful night. No one else, not even Scott, finds out until her body is found. The film shakes things up a bit: We never see the moment, but Megan told Abdic about the pregnancy, presumably after she revealed what happened to her first baby. When Abdic is brought in for questioning, he tells the police, and they tell Scott (along with some truths about Rachel), sending him into a rage.

13. From Clara to Martha

Of the many lies Tom tells Rachel about her blackouts in the book, one of the worst involves a drunken altercation with his boss’ wife, Clara. In the film she’s played by Lisa Kudrow and her name is Martha. Though we never meet her in the book, the newly-dubbed Martha has a small but crucial role in the film. Via flashback, we see Tom’s version of the incident, which involves a belligerent Rachel yelling at Martha, throwing deviled eggs at a brick wall and getting her husband fired. During a key scene later in the film, Rachel runs into Martha on the train and apologizes for her past behavior, but a baffled Martha reveals that Rachel didn’t attack anyone, and we learn that Tom made it all up.

It’s a simple but effective way to reveal Tom’s manipulative actions, but the film lacks the build-up from the book, in which Rachel spends more time reflecting on what she did (or what Tom says she did) during her blackouts, and how that could somehow implicate her in Megan’s disappearance.

It’s also a terrible waste of Kudrow, and the second film this year that uses a character named Martha as a pivotal — and laughable — plot device.

Universal

14. The turn of the corkscrew

The big climax and confrontation with Tom is almost exactly the same as it is in Hawkins’ novel, but in the film, Anna doesn’t retreat to protect baby Evie, nor does she play the part of willfully oblivious enabler. Instead, she removes herself from the equation while a truncated version of Tom relentlessly abusing Rachel plays out into the backyard. There, just as she does in the book, Rachel defends herself by shoving a corkscrew into Tom’s throat — a symbolic gesture that’s even more heavy-handed on screen. Anna eventually joins them, and instead of saving Tom, she twists the corkscrew even deeper. It’s kind of silly and over-the-top, but it’s the only time that Ferguson appears to be awake.

15. The end

At the end of the novel, Rachel visits Megan’s grave and finds that baby Libby’s headstone has been moved and placed next to her mother, now that the police have determined that Megan wasn’t some vicious baby-killer. With the help of her mom, Rachel is getting back on her feet, though she’s haunted by her trauma. She stops drinking, but acknowledges that the desire remains.

At the end of the film, Rachel (now looking more polished) visits Megan’s grave, but there’s no marker for Libby. Rachel gets back on the train as her optimistic voiceover explains that she’s looking forward to the future and she’s no longer the girl she once was.