Gone Girl

The truth behind Amy Dunne's disappearance turns out to be a meticulously staged revenge plot against her husband. Furious over Nick's affair with a young former student named Andie, and contemptuous of the man he'd become, Amy spent months planning to disappear and frame Nick for her murder, ensuring he would be convicted or driven to suicide. She faked entries in a diary portraying him as controlling and frightening, planted evidence, ran up debt in his name, and left behind an elaborate treasure hunt of clues for their anniversary that would make him look guilty. She then went into hiding, first at a cheap motel where she was robbed of most of her hidden cash by a couple named Greta and Jeff, and then, out of money and options, she turned to Desi Collings, an obsessive ex-boyfriend who took her in at his family's lake house in the Ozarks.

Meanwhile, Nick, helped by his twin sister Margo and his lawyer Tanner Bolt, works through Amy's clues and slowly realizes she engineered the entire disappearance to destroy him. Rather than collapse under the frame-up, he goes on television and gives a calculated, emotional performance appealing directly to Amy, apologizing and professing love, gambling that her vanity and need for control will draw her back to him. Watching from Desi's house, Amy is moved by the performance and decides to return to Nick, but she needs an exit from Desi and a story that will restore her image as a victim rather than a murderer. She kills Desi, slitting his throat during a staged sexual encounter, and mutilates the scene to make it appear he held her captive and raped her.

Amy shows up at home covered in blood, claiming she escaped a kidnapper who had obsessed over her since childhood and that she killed him in self-defense. The police and public embrace this account, and the case against Nick evaporates. Nick alone understands what actually happened, but he has no proof and no way to expose her without destroying himself in the process, since Amy still holds evidence that could send him to prison. He resolves to leave her once it's safe, and begins secretly writing an account of the truth.

Amy then reveals she is pregnant, having secretly retrieved and used Nick's stored sperm sample from an earlier fertility procedure to inseminate herself without his knowledge. Confronted with the reality that Amy would raise their child alone and unchecked if he left, and unable to walk away from being a father, Nick chooses to stay in the marriage. The novel closes with the two of them locked together in a relationship built on mutual manipulation and fear, Amy fully in control, and Nick resigned to living with the woman he now understands to be dangerous, brilliant, and utterly unwilling to lose.

Gillian Flynn adapted her own novel, and the ending comes through intact: Amy gets away with all of it, and Nick stays. In both versions she inseminates herself with the sperm the two of them had banked at a fertility clinic, and in both the people who know exactly what she did — Nick, Go, Detective Boney — have no proof of any of it.

What changes is where the last beat is played. The novel keeps it private. Nick has been made to delete the exposé he was writing, has settled into performing the perfect husband, and on the eve of Amy's due date lets the performance slip far enough to tell her he pities her — which unsettles her more than anything else in the book. Fincher makes it public instead. Amy times the reveal of her pregnancy to minutes before a television interview, Nick reacts violently but decides to stay because he feels responsible for the child, and the film closes on the two of them announcing the baby on television.