Nick Dunne, portrayed by Ben Affleck, is seen tenderly stroking the hair of his wife, Amy, played by Rosamund Pike, while voicing a chilling thought through an internal monologue: he wishes he could crack her skull open and sift through her brain to uncover the mysteries that plague every married couple—What are you thinking?
On July 5, 2012, as dawn breaks, Nick takes out the garbage and surveys their quiet neighborhood before heading to a bar he co-owns with his sister, Margo (played by Carrie Coon). He brings her a Mastermind board game, which she dismissively throws into a pile of others, and orders a drink, indicating her disinterest in his choice. Although it’s their 5th wedding anniversary, Nick appears detached, bracing himself for yet another of Amy's scavenger hunts.
Flashing back to January 8, 2005, we see the couple meet at a New York party. Nick, a writer for a men's magazine, is instantly drawn to Amy, who creates personality quizzes. Their flirtation is underscored by Amy's teasing comment about Nick's cleft chin—prompting him to cover it with his fingers, trying to appear more trustworthy. Moments later, under a cascade of sugar from a bakery delivery, they share an impulsive kiss that quickly intensifies inside her apartment.
Returning to the present, Nick receives a call from a neighbor about their cat roaming outside, prompting him to search for Amy, only to discover a scene of chaos at home—a flipped table and shattered glass. Panic sets in, and he calls the police, leading to Detective Rhonda Boney and Officer Jim Gilpin (played by Kim Dickens and Patrick Fugit, respectively) arriving at the scene. They discover small blood splatters in the kitchen and a disturbing wall filled with photos of Amazing Amy, the fictional character from the books created by Amy’s parents. Rhonda, shocked to learn that Nick is Amy's husband, shares her admiration for the series.
The narrative continues to weave through key moments in Nick and Amy's life together, including an unsettling party hosted by Amy's parents in February 2007, where Nick's unease begins to surface. Meanwhile, Amy is put in the spotlight as she grapples with her parents' expectations and reflects on how their real family life starkly contrasts the Amazing Amy character.
As the investigation into Amy's shocking disappearance unfolds, Nick's demeanor becomes increasingly questionable. His indifference during police questioning causes alarm, and as the media frenzy intensifies, Nick's public image is scrutinized. People speculate about his involvement, leading to tense interactions with both detectives and reporters at a volunteer center.
While searching for answers, Nick grapples with his increasingly complicated marriage. Hidden diary entries reveal Amy's downward spiral, contrasting the couple's once blissful moments against a backdrop of financial turmoil and feelings of entrapment. The film artfully juxtaposes romantic flashbacks with the current drama, spiraling towards Amy's calculated disappearance.
In a shocking twist, it's revealed that Amy is alive and has meticulously orchestrated her own vanishing act to frame Nick for murder. Under the ruse of a victim, she carefully plants evidence to ensure her husband appears guilty. The story takes dark turns as she resorts to manipulating her own narrative and enacts violent schemes against those who wronged her.
As the investigation and media scrutiny escalate, Nick seeks legal help from Tanner Bolt (Tyler Perry), eventually leading to televised interviews aimed at clarifying his actions. Amidst mounting tension with Amy's calculated return ultimately threatens Nick's very existence.
The film culminates in a chilling reunion where, despite Nick's heart-wrenching realization of Amy's manipulations, he finds himself ensnared in her web of deceit as she produces a positive pregnancy test—an undeniable trap to bind him to her forever. The saga closes where it began, with Nick caressing Amy's hair, swallowed by doubt about her true intentions yet again, pondering what thoughts lie hidden behind her eyes.
