In 1932, Violet Speedwell is a 38-year-old unmarried typist living alone in Winchester, England. She is one of Britain's two million "surplus women," a generation left single after the First World War killed so many young men. Her elder brother George died at the Battle of Delville Wood in 1916, and her fiancé Laurence Furniss was killed at Passchendaele a year later. These losses shattered her family: Her mother, Mrs Speedwell, became consumed by grief, while Violet withdrew into quiet despair. Six months before the novel opens, Violet fled her mother's suffocating household in Southampton for a rented room in Winchester, a move Mrs Speedwell condemned as treachery. Her younger brother Tom, who survived the War and married, drove Violet to Winchester and counseled her to build a life there. Living on a meager salary, Violet can barely afford to eat, but she treasures her fragile independence.
One Thursday afternoon, Violet wanders into Winchester Cathedral during a special service and discovers the Winchester Cathedral Broderers, a group of women organized by Louisa Pesel to embroider kneelers and cushions for the Cathedral's choir stalls and presbytery, the area near the altar. The colorful kneelers intrigue her, as does Gilda Hill, a talkative woman who sits beside her and peppers her with questions. Violet later learns that Gilda is the sister of her office mate Olive's fiancé.
In the weeks that follow, Violet examines a kneeler during Evensong, the Cathedral's evening service, and meets its maker, Dorothy Jordan, a Latin teacher who directs Violet to join the broderers. At her first meeting, the group's domineering co-leader Mrs Biggins assigns Violet to sort a cupboard, but Louisa Pesel takes Violet under her wing and teaches her foundational embroidery stitches. Pesel's warm authority draws Violet immediately into the work.
As Violet's skills develop, so does her life in Winchester. Her office mate Olive leaves abruptly after becoming pregnant, and Violet proposes that she and her colleague Maureen absorb Olive's work in exchange for a raise, saving the company a full salary. She teaches Maureen to embroider, transforming their strained relationship. Gilda becomes Violet's closest friend and introduces her to Arthur Knight, a 60-year-old Cathedral bellringer with white hair and bright blue eyes. Arthur's warmth and directness affect Violet deeply. When a memory of George triggers sudden tears, Arthur offers his handkerchief with quiet understanding. Violet keeps it.
Over the summer, Pesel grants Violet permission to make her own kneeler, and Violet becomes absorbed in stitching. She takes a solo walking holiday from Winchester to Salisbury and on to the Isle of Wight. During the walk, a menacing stranger follows her through a cornfield. She flees to an inn, where he reappears at the bar, having taken a shortcut. She later learns his name is Jack Wells.
At Nether Wallop, Violet encounters Arthur in his garden. His wife Jean sits nearby with her eyes closed. Arthur closes the gate carefully and walks away with Violet. That evening, he reveals that he and Jean lost their son Jimmy at Passchendaele. When Violet spots Jack Wells watching from the bar, Arthur promises to look into it. The next morning, Arthur walks Violet partway to Salisbury, explaining the mathematical principles of change-ringing, where bells sound through permutations that never repeat.
Back in Winchester that autumn, Violet presents her completed kneeler and notices a charged undercurrent between Gilda and Dorothy that provokes whispers from other broderers. At the Presentation of Embroideries, Violet places her kneeler beneath centuries-old bellringing graffiti and touches her embroidered initials: VS. Her mark. Arthur invites Violet to see the Cathedral bells, leading her through the ringing chamber and the bell chamber above it. During the service ring, she watches the men pull their ropes in focused coordination and experiences a transcendent fusion of movement and sound. Arthur reveals that Jean was the last woman to ring in the tower, on the day before they learned Jimmy had died. Jean connected the Cathedral with the terrible news and refused to return.
At Christmas Midnight Mass, Violet's worlds converge. Gilda clutches a pair of bottle green gloves, a Christmas present from Dorothy, and reveals that Dorothy came to the Cathedral to see her. Violet realizes this is what love looks like. On New Year's Eve, Jack Wells follows Violet across the dark Outer Close, the open precinct surrounding the Cathedral. She runs to the bell tower, finds a hidden spare key, and locks herself inside. Her arrival disrupts the midnight peal; Arthur and his fellow bellringer Keith Bain sit out the ringing to help her, and the Tower Captain bans both men for a month. Afterward, Gilda confronts Violet about her feelings for Arthur and confesses her relationship with Dorothy. They negotiate a mutual understanding, each asking the other not to judge.
In January, Dorothy is dismissed from her teaching position and expelled from her family's home after her relationship with Gilda is discovered. Violet telephones Louisa Pesel, who arranges lodging without hesitation: "Broderers look after their own." Violet also persuades her supervisor, Mr Waterman, to commission Dorothy to make embroidered cushions for his wife's dining room chairs, providing paid work.
When Violet's mother has a minor stroke, Violet returns to Southampton to nurse her. During two weeks of enforced closeness, mother and daughter reach a fragile truce. Rather than moving back permanently, Violet proposes that Dorothy become Mrs Speedwell's live-in companion. Back in Winchester, Arthur takes Violet's hand in the Fishermen's Chapel, distraught over Hitler's rise. Later, he confronts Violet about swastika motifs in a cushion border she deliberately stitched to reclaim the ancient symbol, called a fylfot, from its Nazi association. Louisa Pesel resolves the dispute by showing them identical symbols on a 14th-century bishop's tomb and declares: "A single thread can make quite a difference."
In May, Arthur teaches Violet to ring a bell at Nether Wallop church. On the ride back, they part at a crossroads. Violet, understanding this may be their only chance, climbs a gate into a field and asks Arthur to join her. He does. Afterward, they agree to have no further contact because his wife needs him. As Violet prepares to leave, Jack Wells appears and attacks her. She stabs him with an embroidery needle hidden in a needle case her niece Marjory made, escapes on her bicycle, and rides to the Cathedral. Sitting on the Tree of Life cushion, she senses a faint change within her body.
Months later, Violet's pregnancy becomes visible. She resigns from her job before Mr Waterman can dismiss her and moves to the family's Southampton house, where Gilda and Dorothy join her, their salaries supporting the household. She sees Arthur only once more: They stare at each other across the Cathedral Close, her bump visible. She nods; he wipes his eyes.
In the final scene, Violet brings her infant daughter Iris to Winchester for a christening in the Cathedral's Fishermen's Chapel. Mrs Speedwell arrives unexpectedly on Tom's arm, her first contact with Violet since learning of the pregnancy. She remains critical but engages, noting that Iris has her late husband Geoffrey's eyes. After the ceremony, a single Cathedral bell begins to ring. Maureen, now married to Keith Bain, whispers that Keith told Arthur the christening was finished: "It's his gift to Iris." Violet listens, holding her daughter, and Iris smiles at the sound of her father's bell.