Jake Fisher, a political science professor at Lanford College, attends a small wedding in a white chapel in Kraftboro, Vermont, watching the woman he loves marry another man. Jake and Natalie Avery, a painter, met that summer at neighboring retreats and fell deeply in love over three months. Without warning, Natalie ended things, leaving a note that she was marrying her old boyfriend, Todd. After the ceremony, Natalie confronts Jake and makes him promise never to contact her or search for her. Jake agrees and keeps the promise for six years.
During office hours, Jake spots an obituary on the Lanford website for Todd Sanderson, a college alumnus and member of Jake's own fraternity. The photograph resembles the groom, though the hair and grooming differ, and the obituary lists Todd as survived by his wife and two children. Jake's closest friend, Benedict Edwards, a humanities professor, suggests mistaken identity, but Jake flies to Todd's funeral in Palmetto Bluff, South Carolina. He never sees Natalie. A barmaid tells Jake that Todd was murdered during an apparent robbery and that his wife is a woman named Delia Sanderson, his high school sweetheart. According to this account, Natalie played no role in Todd's life.
Back at Lanford, Jake searches for answers. He finds nothing current on Natalie online and asks Mrs. Dinsmore, the department receptionist, to pull Todd's student file. He enlists Professor Shanta Newlin, a colleague with FBI contacts, to locate Natalie, and calls Natalie's sister, Julie Pottham, who denies knowing him. Jake drives to Vermont and finds the Creative Recharge Colony, the artists' retreat where Natalie once stayed, sealed off, with police insisting no retreat ever existed. At the chapel, the registrar finds no record of Natalie's wedding, and the minister who presided over it denies any memory of the ceremony.
Todd's student file reveals outstanding grades followed by a leave of absence and a violent altercation. Professor Eban Trainor, a Lanford colleague, explains that Todd's father was falsely accused in a scandal and died by suicide. When a classmate taunted Todd, Todd attacked him. Professor Malcolm Hume, Jake's mentor, defended Todd and helped him found a charity called Fresh Start. That night, Jake receives an anonymous e-mail: "You made a promise." His reply bounces back.
Shanta reports that Natalie has effectively ceased to exist: no address, tax records, or bank accounts. At 3 A.M., a man named Bob who has been following Jake appears in his apartment and orders him into a gray van. Bob's partner, Otto, attacks Jake's student Barry Watkins and draws a gun to force compliance. Inside the van, Jake sees handcuffs welded to the wall and a toolbox of blades. Bob demands Natalie's location. In the struggle that follows, Jake kills Otto by crushing his windpipe, escapes, and tumbles down a hillside into unconsciousness.
Police dismiss Jake's account, finding no evidence. The college president places Jake on leave. Jake returns to Palmetto Bluff and visits Delia, posing as a college representative. Delia reveals that Todd's killers tortured him with tools before shooting him. As Jake leaves, he spots Natalie's painting of a cottage on a hill above the fireplace, confirming that Delia's Todd is the same man who married Natalie.
Shanta uncovers that Natalie's father, Aaron Kleiner, was a political science professor at Lanford who vanished 25 years earlier, after which the family changed their surname to Avery. Cookie, the baker who first introduced Jake to Natalie, calls in distress and lures him back to Vermont, where a man named Jed, who owns the retreat property, holds Cookie at gunpoint. Jed, whom Jake recognizes from the night he met Natalie, accuses Jake of killing Todd. When a police car appears on a surveillance feed, Jake leaps through a window and escapes. Cookie finds him in the woods, guides him to his car, and warns that his search endangers many lives.
Jake confronts Julie in person. She admits she has not seen Natalie in six years and reveals that Todd was not an old boyfriend but someone Natalie had just met. Police surround Julie's house, having tracked Jake's disposable phone after Shanta provided the number. At a precinct, detectives show Jake a mug shot of Otto Devereaux, the man he killed, calling him a hero for eliminating a notorious enforcer. They reveal a surveillance still of Natalie fleeing a building corridor six years earlier and warn that dangerous people are hunting her.
Jake attends Otto's funeral and follows one of Bob's associates, learning that Bob's real name is Danny Zuker, a lieutenant in the crime syndicate of mob boss Maxwell Minor. Investigating Benedict's car GPS, Jake discovers that the most recent destination is the Vermont retreat. He uncovers his friend's true identity: Jamal W. Langston, a Ghanaian prosecutor who faked his death to escape drug cartels. Fresh Start gave Benedict a new life. Benedict explains that the organization rescues people who need to vanish, gives them new identities, and ensures no one knows their final destinations. He begs Jake to stop, warning that the search could get Natalie and others killed.
Jake nearly relents but realizes Todd's murder preceded his involvement, meaning Natalie may already be in danger. Researching the date on Natalie's surveillance photo, Jake discovers the murder of Archer Minor, a lawyer who denounced his father Maxwell Minor's criminal empire. Natalie was in the building that night. Jake visits Natalie's mother, Sylvia Avery, who reveals that Aaron Kleiner did not abandon his family. Archer Minor, then a Lanford student, cheated in Aaron's class, and when Aaron reported it, the Minor family terrorized the Kleiners until Aaron was forced to disappear. Sylvia lied to her daughters to protect them, but Natalie eventually pressed the truth out of her.
Shanta connects a final thread: during a series of bank robberies, thieves broke into Todd Sanderson's safety-deposit box and found Natalie's will. Jake deduces that someone reported her name to the Minors, leading Zuker and Otto to torture and kill Todd. Jake drives to Malcolm Hume's remote cabin and finds the cottage from Natalie's painting. Inside, Malcolm lies dead, having swallowed the cyanide capsule all Fresh Start members carry. Jed tells Jake that Zuker's men found the cabin, then charges outside firing to buy Jake time and is killed. Zuker's henchmen corner Jake, but two rifle shots from the hillside cut them down. Natalie, having tracked the crisis to the cabin, emerges from the woods with a gun. Zuker seizes Jake as a shield and demands her surrender. As Natalie lowers her weapon, Jake forces the cyanide capsule into Zuker's mouth. Zuker fires, hitting Jake in the shoulder, and the poison takes effect as Natalie shoots Zuker dead.
Natalie tells Jake she must disappear again. Jake, bleeding, runs after her and refuses to let go. This time, she stays. One year later, Jake narrates under a new identity, living in New Mexico with Natalie. In a final visit to Sylvia before entering witness protection, he learned the last truth: Archer Minor did not merely drive Aaron into hiding but murdered him in the family home. Jake understands that Natalie went to Archer's office to confront her father's killer, and that Maxwell Minor hunts her to avenge his son. Jake does not ask what happened that night. He watches his pregnant wife, now Diana Weiss, teach an art class in the sun. She looks up, smiles, and tells him she loves him.