Eli, a 27-year-old graduate student in Brooklyn, is working on a stalled thesis about dying languages when his girlfriend, Lilia, disappears on the last day of October. She tells him she is going out for the paper, kisses the top of his head, and never returns. Her comb and toothbrush remain, but her only childhood photograph has been removed from the wall and her suitcase is gone.
The novel moves between this crisis and the story of Lilia's childhood. When Lilia is seven, her father appears beneath her bedroom window on a snowy night south of Montreal and motions for silence. She runs barefoot into the snow; he lifts her into his arms and carries her into the forest while her nine-year-old half-brother, Simon, watches from a window. In the morning, their mother calls the police but first instructs Simon to help hide broken glass from a shattered kitchen window and bottles of Scotch, replacing them with a cover story. What follows are years of ceaseless travel across the United States: motel rooms, false names, dyed hair, and constant motion. Lilia's father teaches her languages but refuses to discuss "Before," his term for their former life and especially for Lilia's mother. Lilia begins keeping lists of her aliases and leaving messages in motel-room Bibles: "I don't want to be found."
Before meeting Lilia, Eli drifted through a life he found unsatisfying, working at an art gallery he despises and comparing himself unfavorably to his brother Zed, who does humanitarian work abroad. He meets Lilia at a Brooklyn café where he has been watching her read for weeks. They talk for hours about endangered languages and the concepts that vanish when a language dies. She speaks four and a half languages, has lived in over 20 cities, and moves in with him three months later.
Their cohabitation is fragile. Lilia has ritualistic habits and gives the impression of harboring enormous secrets. Eli discovers lists and a private investigator's business card in her suitcase. Confronted, Lilia begins telling her story over several nights, but all her stories are about leaving. When Eli asks if she will leave him, she answers, "I don't know." In a desperate gesture of tenderness, he feeds her pomegranate seeds by flashlight under the duvet until she stops crying.
A parallel storyline introduces Christopher Graydon, a 45-year-old Montreal detective who takes a leave of absence to pursue Lilia's missing-persons case for Peter, a private investigator hired by Lilia's mother. Christopher's home life is deteriorating: His wife, Elaine, is having an affair, and his daughter, Michaela, a gifted tightrope walker who attends circus school, grows increasingly neglected. Christopher traces a phone call from an Arizona pay phone to Lilia's mother's house and travels south, spending weeks interviewing motel staff and collecting the Bibles in which Lilia has written.
Around age 11, Lilia sees herself on the television show
Unsolved Cases in a motel room in Arizona. Her mother appears on the program and says she wishes she could forget her daughter. Panicked, Lilia calls the phone number she inexplicably remembers. Simon answers and, instead of urging her home, whispers for her to keep travelling.
Christopher's obsession deepens until he is following Lilia and her father across the country, watching from a distance rather than apprehending them. His absence destroys his family: Elaine leaves, and Christopher disappears for a year. Michaela, alone at 15, blames Lilia for the dissolution of her family.
Lilia's father eventually settles in Stillspell, a near-ghost town in New Mexico, with Clara, a waitress. Christopher visits the area and tells Clara he has spoken to Simon and understands the abduction was justified; he asks her never to go to the police. But Lilia, approaching 16, cannot stop moving and begins travelling alone, passing through dozens of cities and leaving a trail of lovers behind.
The secret at the novel's center is a car accident two days after Lilia's 16th birthday. On a mountain highway, Lilia's father pulls over sharply. Christopher's car passes and stops on the shoulder ahead. Christopher walks back and tells them he is done pursuing them; he has spoken to Simon and understands why Lilia was taken. He wishes Lilia a happy birthday and drives away. Lilia's father, convinced it is a trap, chases Christopher's car and methodically forces it off the road. Christopher meets Lilia's eyes, smiles, and makes no effort to resist. His car slides off the embankment and crashes into a tree. Christopher returns to Montreal using a wheelchair, eventually progressing to a cane. Lilia tells Eli this story in bed in Brooklyn, making him promise never to share it.
Four weeks after Lilia's departure, Eli receives a postcard from Montreal signed by Michaela, directing him to Club Electrolite on Rue Sainte-Catherine. A second envelope contains a torn Bible page with Lilia's childhood handwriting: "I wish to remain vanishing." Eli takes a train to Montreal, arriving without luggage or knowledge of French. He encounters Michaela walking a tightrope between buildings two storeys above an alleyway with no safety net. At Club Electrolite, she reveals that her father was the detective on Lilia's case and demands the accident story in exchange for Lilia's location.
Over weeks of nightly meetings at an all-night café, Michaela holds Lilia's location as currency. She has an addiction to prescription medications and sleeps on a child-sized mattress in her dressing room at the club. Finally, Eli breaks his promise and tells her about the accident. In return, Michaela gives him the address of Lilia's rented room and reveals what she told Lilia earlier that night: that Lilia's mother threw seven-year-old Lilia through a window, and Simon found her bleeding in the snow and called her father to take her away. This truth explains the bandaged arms Lilia had on the night of her abduction.
As Eli walks toward Lilia's building, Michaela's parting words register: "Say goodbye to her for me." He turns and runs back to the Métro Place-des-Arts station. Michaela stands at the platform edge, poised like a tightrope walker, and steps in front of an oncoming train. Eli screams but cannot reach her.
Eli collapses and is hospitalized for weeks, unable to speak. His brother Zed arrives, having found an unmailed letter in Eli's jacket, and brings him home to their mother's apartment on the Upper West Side. Recuperating in his childhood bedroom, a room painted like a seascape with a bed made from a fishing boat hull, Eli tells Zed he wants to travel genuinely into the world.
Lilia flees Montreal the night of Michaela's death and flies to Rome. She drops her three lists from a bridge into the Tiber River and calls Simon to thank him. Ten years later, she lives in Rome with her Italian husband. Memories surface at odd moments, but her life of compulsive flight is over. Simon, now grown, still dials the Arizona pay phone number he recorded as a child. No one answers, but he is soothed by the static. In Leonard, Arizona, a pay phone by a truck stop sometimes rings at night.