Few book-to-film adaptations speed past their source material — The Silence of the Lambs, Jaws, and The Godfather are in an exclusive club. Films are forced to cut characters, rush scenes, and by the very nature of the medium, reduce the extent to which the audience is privy to characters’ inner lives. But every so often comes a novel that has the makings of a much better film. Here’s why The Girl on The Train is one.

The book is actually quite average. This might sound like a head-scratcher: After all, you can’t draw a great story out of material that just isn’t in the original. For example, 50 Shades of Grey is a poorly written novel with a plot thinner than cellophane and almost as see-through, so it was never going to make a decent movie no matter how hard the filmmakers or actors tried. The novel Divergent is a blatant rip-off of The Hunger Games and Harry Potter, so the movie was never not going to be a similarly blatant rip-off.

But that’s the rub: The Girl on the Train is not a poor story: the plot, while a little too thin, is a solid thriller, with equal parts Rear Window and Gone Girl, as it centers on an alcoholic divorcee who spends her daily train commute spying on a suburban couple and fantasizing about their perfect life — until one day the woman goes missing. The characters, while under-developed, are interesting. The material has enough potential to expand into something compelling, so it leaves the film room to improve upon these things, so long as the writing and acting is there. Which brings us to…

Emily Blunt. Protagonist Rachel is a self-pitying alcoholic who can’t let go of her ex-husband and lies her way into a truly creepy relationship with a missing woman’s husband. In the book, she’s unlikable; it’s grating to be in her head. But Emily Blunt is such a fine actress that watching her be a terrible person is fun. Rachel will be far more successful in the hands of a great actress than she was in print. There’s precedent for such a page-to-screen progression, in fact, and she wore Prada.

Justin Theroux. Similarly, Rachel’s ex-husband — SPOILER ALERT — is revealed, in a lame twist, to have been evil all along, without Rachel ever noticing. In the book, this reads as a desperation plot twist pulled straight out of the author’s ass. One moment, he’s a mild-mannered suburban dad; the next, surprise, he’s a sociopath! If you only know Justin Theroux as “that guy Jennifer Aniston married who is always on the cover of every supermarket tabloid,” forget that. He’s a phenomenally strong actor who is the heart and soul of HBO’s most-improved show ever, the alarmingly good The Leftovers. Theroux’s face of pissed-off distress is second to none. In every scene he’s in, he plays about five different emotions at once.

In the Girl on The Train, Tom has the potential to be an intriguing character, but the author rushes the “by the way, he’s evil!” development and the narrative never quite delivers. But in Justin Theroux’s hands, Tom is sure to be a memorable and chilling character.

Director Tate Taylor. Despite having a name that sounds like he’s the jock in a made-for-TV movie about teen pregnancy, Tate Taylor is a highly capable actor and director. He’s was in Winter’s Bone, the raw, searing film that made Jennifer Lawrence before she was Jennifer Lawrence.

He also directed The Help. The Girl on The Train’s biggest issues were its jumpy pacing and the aforementioned rushed ending. Taylor’s deft hand made The Help perfectly paced.

Most book-to-film adaptations produce mediocre films from mediocre books, or middling films from good books — but every so often, the stars align for a great movie to spring from a novel that’s merely a’ight. Between its cast, its director, and the latent potential in its source material, The Girl On The Train will be that rare film that exceeds the book. It hits theaters on October 7th, 2016.