Luke Devlin works as a baggage handler at Heathrow Airport. He likes his job, but his life is about to change because of his girlfriend Melissa’s birthday and a new arrival at the lost and found. When a coworker notices an aged violin case, Devlin thinks it’s a perfect gift for Melissa’s birthday—she always wanted to learn, but her parents couldn’t afford the lessons. Devlin convinces Pete, the guy in charge of the lost and found, to sell the violin to him.

Melissa’s birthday party ends with paramedics taking her mother to the hospital for heart palpitations. Devlin wonders if he and Melissa should’ve gone with her, but Melissa says her mother is dramatic when she’s stressed. Melissa sits on the window seat she and Devlin built together, a process she filmed for Instagram. She has curated their apartment into an Instagram-appropriate space, and Devlin misses his wicker coffee table.

She tells Devlin that she’s embarrassed because she, her mother, and her friends all thought he would propose, since it’s Melissa’s 30th birthday. Devlin thinks he loves Melissa and wants to settle down, but he can’t bring himself to do it.

Melissa looks at the violin he gave her, and Devlin brings up the time she said she wished she could learn, but she doesn’t remember. She leaves the room, and he holds the violin against his chest, feeling a strange sense of comfort, though it’s been years since he played a musical instrument. He plucks a string and hums along and feels at home again, as if a missing piece of himself has returned.

At work, Devlin sees a newspaper open and reads a headline that reads “priceless violin stolen” (10). He realizes that the violin he bought from the lost and found was stolen from Christie’s Auction House. After heiress Margot Clement died at age 104, authorities discovered the violin in her London apartment. They dated it to the 1700s and appraised it at £10 million. Devlin knows he should return the violin to the authorities, but he feels drawn to it.

Walter Pickering fills his car up with gas before realizing he forgot his wallet at home. He’s been having more memory lapses since he retired from teaching history. The clerk refuses to let Walter drive home and retrieve his wallet to pay.

Defeated, Walter walks home to his apartment, thinking about his loneliness. Walter was an only child and never found a romantic partner, but he didn’t know he was lonely until he retired. Now, he struggles to find a human connection, even with his neighbors. He arrives home and listens to a symphony that composer Gustav Mahler wrote for his wife, and he wonders what it would be like to love someone so desperately. Walter wonders who would even miss him. He pours himself a glass of brandy and empties a bottle of painkillers into his hand. Before he can take them, the doorbell rings.

Devlin stands on Walter’s doorstep with the violin. He shakes Walter’s hand enthusiastically, but Walter, who recognizes Devlin as a previous student, is unsure why he’s there. Devlin loved Walter’s history class, and he believes that Walter saw through Devlin’s bravado and “spoke to the man he might become” (20). He tells Walter he needs his help, and Walter invites him inside.

Devlin sees the brandy and the pills and asks Walter if he’s alright, but Walter breezes past it. He questions Devlin about the violin, recalling that Devlin played guitar. Devlin feels honored that Walter remembers him, and Walter begins to make them sandwiches to eat while discussing the violin.

Gabrielle Wilding sits in the flat above her shop and reads a dusty book about a lost romanza that the great Niccolò Paganini wrote for his beloved mistress. Gabrielle’s secret passion is searching for lost music. She runs her father’s fine instrument appraisal shop after he “sacrificed himself” to save the business, but she barely makes enough to cover the bills. Gabrielle finds Paganini’s work enticing and passionate and wonders what a love like that would feel like. Paganini’s work was her favorite to play on the violin before her injury, when she studied under talented soloist Max Daunt. She refuses to wallow, but she thinks her chance at a remarkable life has already passed her by.

As the chapter closes, the phone rings.

Devlin tells Walter everything he knows about the violin. Walter wonders why Devlin didn’t call the police, and Devlin explains that he’s worried a criminal gang will come after him, and he doesn’t want to get himself or Pete fired for selling the violin. Walter thinks they should search for the violin’s rightful owner, and Devlin agrees. He spends the night on a camp bed in Walter’s living room. He texts Melissa, who responds indifferently.

He wakes to Walter making him breakfast. Walter tells Devlin that they should have the violin appraised to ensure it really is the stolen violin. He finds the number of Mr. Wilding, who can assess it for them. Devlin and Walter take the tube to Wilding’s shop.

Walter reflects on his loneliness. He’s glad he didn’t attempt to die by suicide, but he knows the loneliness will return after the adventure with the violin ends. For now, he focuses on the purpose of solving the violin’s mystery.

Walter and Devlin enter Wilding’s. Gabrielle greets them, and Walter asks for Mr. Wilding. Devlin is awestruck by Gabrielle’s beauty and intensity. Gabrielle tells Walter that her father is dead, and she now runs the shop.

Devlin gives the violin to Gabrielle, who explains that she’ll have to take it apart to appraise it. Devlin worries aloud that that’s invasive, but Gabrielle insists. Walter trusts Gabrielle and thanks her. Walter and Devlin go to a pub afterward, and Walter identifies that Devlin finds Gabrielle attractive. Devlin wonders if he can trust Gabrielle, but he knows he must trust Walter.

After the men leave, Gabrielle opens the violin’s case. She immediately finds the violin beautiful and thinks it’s valuable. She can’t find any stamps on it from a luthier (violinmaker).

Gabrielle remembers her mother, a London Symphony Orchestra violinist, before she became ill. Gabrielle began playing for her mother, and after her mother died, Gabrielle begged her father for lessons with Max Daunt, a prominent tutor.

Gabrielle picks up the violin and begins to play “Danse Macabre” by Saint-Saëns, the same song she played during her final performance, when her wrist pain began. Doctors haven’t been able to explain the debilitating chronic pain in her wrist. However, as she plays the mysterious violin, her wrist doesn’t hurt at all. She wonders if the violin can bring her back to life.

Walter goes to the British Library to research Margot Clement’s family. He finds two potential heirs, one in New York and one in Somerset. Meanwhile, Gabrielle goes to the library to research Paganini’s missing piece “Bellezza Nascosta,” and she finds an article from 1903 that references a new discovery of Paganini’s work but not the specific romanza Gabrielle seeks. Gabrielle runs into Walter and asks him to coffee.

As they drink coffee, Gabrielle warms to Walter, and Walter realizes her frosty exterior hides her interior pain. Gabrielle reveals that she played the violin. Her mom used to say playing the violin was like “birds singing in their sleep” (56), as a study from Argentina revealed songbirds sing in their sleep as if they are practicing their notes. Walter tells Gabrielle that nature has a way of reminding people of the beauty of the world.

Verity, an antique shop owner, meets with two biker gang members from Quebec City. The two men inform her that they successfully stole the violin from Christie’s. They took it to the airport, and after drinking at the airport bar, accidentally grabbed the wrong bag. They give it to her. Verity is enraged—she wants the violin her father lost to a Middle Eastern prince years ago.

She calls the phone number on the tag of the bag and asks the woman if she has the other bag. The woman admits that she forgot her bag at the bar, but she didn’t pick up another one. Verity hangs up and tells the two men that they must accompany her to London to finish the job or forfeit their $50,000 payment.