Even the worst marriages exist in languages that only the two participants speak. They're a series of gestures and secrets, inside jokes and barely perceptible facial expressions. And when a relationship turns sour, speaking that language becomes a curse, something constantly inviting your spouse in when you might want only to keep them out. And then, finally, you succeed. You forget how to speak it. You lock the other out.

We think of the end of a marriage as a series of legal documents signed, a court hearing and a contract. But it comes earlier than that, and it's far more mundane. It's realizing you knew someone at one time, but you don't any more. And they — willfully or accidentally — have been complicit in that act.

The brilliant Gone Girl, one of the best films of the year, opens with a scene where a man's hand strokes the head of his wife, wondering what she's thinking. "What have we done to each other?" he muses. She looks up at camera, at once very near and in some other universe entirely. These people are locked in a terrible intimacy together, but they're also each trapped in separate rooms of their own construction they can never leave.

What have you made me become?

Gone Girl, adapted for the screen by Gillian Flynn from her novel and directed by David Fincher, is a great many things. It's a potboiler thriller. It's a twisty, turny series of big surprises. It's the blackest of black comedies. It's a series of dueling character studies. It's a bracingly feminist corrective to much Hollywood storytelling, a wicked satire of cable news, and a sleazy crime drama that nonetheless has a surprising amount to say about the American class system.

But above all, it's an examination of a marriage, one that pushes situations all spouses face to ridiculous extremes, of course, but also one that digs into that fundamental inability to ever really know who the person you're married to is. You can be close, co-dependent, even, but you can never really know the part of themselves they keep under the strongest lock and key.

The plot stays fairly close to the book. The morning after Independence Day, Nick Dunne (Ben Affleck) returns home to find his house timidly ransacked and his wife, Amy (Rosamund Pike) missing. As he and the community embark on a search for her that increasingly paints him as an unsympathetic cad who maybe wanted his wife dead — maybe even killed her — the film begins to incorporate flashbacks from Amy's diary, stories that depict a fairytale courtship that headed south when money woes and a parental illness dragged Amy and Nick from New York to small town Missouri.

The film makes the characters come alive in a way they simply didn't on the page

There's more to it than that — as fans of the book will surely know — but it's also one of those "the less you know going in, the better" things. Suffice to say that the book was an intriguing experiment in many ways, but also had the bad habit of making Nick and Amy seem like plot twists walking around in human skin, constantly attempting to evade the reader. By the simple fact of these roles being placed in the hands of actors, the film makes them come alive in a way they simply didn't on the page.

Affleck leans into his inner lunk to make Nick a bit of a doofus who only realizes how everybody else in the world sees him far too late. He's good here, as good as he's been on screen. But it's Pike whom audiences will be talking about and arguing about and discussing long after they've screened the film. She seizes hold of Flynn's conception of a woman slowly losing control over her own narrative with gusto, and Fincher reacts splendidly. There's a sequence around the midpoint — a monologue where Amy lays out everything that Nick has made her become over the course of their marriage — that might be the best thing the director has ever done. It's exhilarating and terrifying and nauseating, the roller coaster of that big fight at 3 a.m. that nearly ended everything, then somehow ended back in safe harbor, encapsulated in one woman's words.

A creative tug-of-war

What's interesting to contemplate about Gone Girl is how, fundamentally, the various creative participants in the movie seem to have subtly different interpretations of what this story even means. Because it's, at heart, a he-said/she-said narrative, Gone Girl essentially invites the audience to decide if it agrees with "he" or "she."

And at times, the script seems to side heavily with Nick, almost to argue that such a fundamentally polite and nice Midwestern boy couldn't have known what he was getting into when he married such a sophisticate. But at all times, Fincher pushes back against this, arguing that the passive-aggressive way American society forces women into roles they don't particularly want is its own kind of bleak violence. His direction often places Nick in the frame in such a way as to make him the butt of the joke, and it keeps tugging away his agency. And, of course, Affleck and Pike become the strongest possible advocates for their own characters.

It is, instead, a struggle marked entirely in emotional violence

Many times, when a director and the script are tugging in different directions, the film is fatally flawed. But it works splendidly here, because that approach turns Gone Girl into a battle, just not a particularly violent one. Blood is spilled, yes, but not as much as you might expect in a movie that opens with a woman going missing and hastily mopped up pools of blood on her kitchen floor. It is, instead, a struggle marked entirely in emotional violence. That phrase — "What have we done to each other?" — resonates throughout the film, both in the literal sense (did Nick kill Amy?) and in the psychological one (how could these two people fall so out of love?).

That all might sound dry and academic, but Fincher and Flynn get away with it because the movie is so damnably fun. Its plot twists are perfectly placed, and its lurid thriller tone peeks through Fincher's classically clinical style just often enough to goose things with a shot of adrenaline. And the movie is wonderfully funny, laced with a mordant wit that reminds you over and over again that these are clever people, who used to have a lot of fun together, and now use that fun as a kind of battering ram against each other, inside jokes weaponized and made harmful. That very bitter wit makes the film's two-and-a-half hours fly by.

Controlling the narrative

Most of all, though, Gone Girl succeeds because it forces us to contemplate who gets to write the narrative of our lives, of our work, of our relationships. We might think of ourselves as in control of how people see us, but we fundamentally aren't. The world will perceive us as it wants to, and it's very easy for that to be twisted by small-town gossip or a media machine hungry for blood.

Everyone in the film's terrific ensemble cast is aware of this on some level or another. Carrie Coon's Margo (Nick's twin sister) knows just enough of how callous her brother can seem to warn him, but not enough to understand how she, too, will be implicated. Tyler Perry's Tanner (Nick's attorney) is a marvelous comic creation, strolling into the film around its middle and attempting to turn things around for Nick with media manipulation skills. Amy's ex-lover Desi (a superbly creepy Neil Patrick Harris) attempts to show her all of the ways Nick has destroyed her, while being oblivious to his own controlling nature. And detectives Rhonda Boney (Kim Dickens) and Jim Gilpin (Patrick Fugit) just try to figure out what the hell happened already.

We all think we're the lead character in the story, but most of us aren't

The beauty of Gone Girl is in how it invites you to empathize and sympathize with every single one of these people, then leaves them all implicated by the end. Any time you are pulled so deeply into someone's circle that you become a part of their lives, you will be left marked and bruised by the occasion. It's just inevitable. We all think we're the lead character in the story, but most of us aren't. And we can react poorly to that. We are primates, after all, and primates lash out when they feel threatened.

"What have we done to each other?" Nick asks as the film begins, and at its heart, Gone Girl knows that for all of the blood shed and all of the horrors uncovered, the worst thing Nick and Amy ever did was assume the other would allow them to be the protagonist in the story of their lives. And as the whirlpool opened, each found, to their horror, the other swimming not to support them but for the opposite side of the drain.