The novel opens with a flash-forward to an April evening at a Magnolia County police station, where rookie Officer Mackie Dodd finds four teenage girls in white ball gowns locked in a holding cell. Interludes throughout the novel return to this scene, as the girls offer competing accounts of how they ended up behind bars.
Nine months earlier, 18-year-old Sawyer Taft lives in a small Southern town, working at an auto garage and managing the household she shares with her mother, Ellie Taft, who tends bar at a local dive and periodically disappears with new boyfriends. Shortly after Ellie takes off again, Lillian Taft, Sawyer's maternal grandmother, arrives unannounced. Lillian, estranged from Ellie since before Sawyer's birth, presents a contract: a $500,000 educational trust in exchange for nine months of living with Lillian and participating in the annual Symphony Ball as a Debutante, a tradition in which young women from prominent families are formally presented to society. When Lillian suggests the arrangement might help Sawyer identify the biological father Ellie has never named, Sawyer signs. Her only clue is a hidden photograph of 24 boys in tuxedos captioned "Symphony Squires," the term for the young men who escort Debutantes, with the year and several faces scratched out.
At Lillian's sprawling home, Sawyer meets her aunt Olivia; Olivia's husband, Uncle J.D.; and her cousin Lily, Lillian's poised namesake. She also befriends Lily's anxious best friend, Sadie-Grace Waters. At the Pearls of Wisdom Charity Auction, Lillian places her legendary pearl necklace on Sawyer to draw attention from men who might have known Ellie. Sawyer learns from Greer Waters, Sadie-Grace's stepmother and chair of the Symphony Ball, that Ellie was once close to Lucas Ames, brother of Senator Sterling Ames. Walker Ames, the senator's son, shows Sawyer a cryptic text from his missing sister, Campbell Ames: "If I'm missing . . . suspect foul play."
That night, Sawyer follows Lily and Sadie-Grace to a house under renovation, where she pockets a Squire photograph and discovers that the men in her mother's photo belong to Olivia's generation, meaning her father was likely an older, married man. Lily then reveals what she has been hiding: Campbell, bound and duct-taped in a pool house. Campbell had been blackmailing Lily over
Secrets on My Skin, Lily's anonymous photo blog where she inscribes strangers' secrets on her body in semi-explicit images. When Lily resisted, Sadie-Grace accidentally knocked Campbell unconscious, and the two panicked and tied her up. Sawyer vows to help find leverage against Campbell.
The plan backfires when Campbell escapes with Lily's tablet, which contains uncropped photos revealing Lily's identity. Campbell issues petty demands, then forces the group to serve as her alibi during a scavenger hunt while she disappears for hours, promising to return all evidence in exchange. That night, police fill the driveway of the Ames estate, and Sawyer learns someone broke into the family safe and stole Lillian's pearls.
At a Halloween masquerade, Campbell surrenders the tablet, but Sawyer witnesses Nick Ryan, a young club employee, arrested. Sawyer suspects Campbell framed Nick for the theft. Nick is released within days but loses his job. Sawyer discovers that Nick's brother, Colt, lies in a coma after a hit-and-run near the club, and that Nick had been working there to investigate.
Lillian identifies four circled faces in the Squire photograph: Uncle J.D., Sadie-Grace's father Charles Waters, Senator Ames, and Thomas Mason, father of Walker's cousin Boone. Boone helps Sawyer obtain paternity tests. The first result eliminates Thomas. In Lillian's attic, Sawyer finds photographs of three inseparable Debutantes: Ellie, Greer, and a girl named Ana, who appear together wearing white ribbons until Christmas, when Ellie and Ana vanish from the photos.
At the Christmas party, Ellie arrives unannounced. Sadie-Grace confides that Greer's pregnancy test was negative and that she has seen Greer trying on fake bellies. Charlotte Ames, the senator's wife, warns Sawyer to stay away from Walker, and when Sawyer asks if the senator is her father, Charlotte does not deny it. Ellie, confronted outside, confirms with a single "Yes" before urging Sawyer to come home.
Sawyer refuses. Her relationship with Lily fractures when Lily accuses her of pursuing Walker, but weeks later Sawyer repairs the rift by revealing the senator is her father, making Walker her half-brother. The cousins reconcile. Sawyer then confronts Campbell, who after weeks of private conversations reveals that the senator was driving the car that hit Colt. He was drunk, struck Colt, then dragged Walker's unconscious body into the driver's seat. Walker's subsequent spiral stems from his false belief that he nearly killed someone. Campbell has been methodically building a case to expose the cover-up.
Sawyer commits to helping. The group hires a lawyer for Nick with money from Lillian's trust. Sawyer wears a recording device and provokes the senator into making threats on tape. Campbell arranges a fallback: Lily photographs the senator's mistress wearing the stolen pearls, which Campbell has planted as a gift sent from his phone. If criminal prosecution fails, the scandal will destroy his career.
On the day of the ball, Sawyer sabotages the senator's car while Sadie-Grace hides in the trunk. Campbell lures her father to the site of the hit-and-run. When the car breaks down, the senator drinks scotch that Sadie-Grace has laced with a sedative. She plants the victim's dog tag in his hand and switches the bottles. The four girls then enter the police station and lock themselves in a holding cell without any officer processing an arrest, staging their own confinement as an alibi. They spend the next hour baffling Officer Mackie until Lillian secures their release, since no arrest record exists. On the way out, the senator is brought in drunk and clutching the incriminating tag. Campbell whispers, "See me now, Daddy?"
The girls reach the ball with minutes to spare. Ellie appears to escort Sawyer, apologizing and acknowledging Sawyer's right to her own life. Sawyer is presented to society with Boone as her Squire. At dinner, Davis Ames, the Ames family patriarch, stuns Sawyer: Sterling is not her father. The senator got a different girl pregnant, Ana. Sawyer realizes she never specified which girl she meant. In the powder room, she catches Greer adjusting the fake belly Sadie-Grace described months earlier. Ellie reveals the full truth: During their Debutante year, Greer initiated a pregnancy pact among the three friends after discovering she was pregnant. Greer lost her baby at Christmas and abandoned Ellie and Ana. The devastating revelation follows: Sawyer was conceived deliberately, and her real father is Uncle J.D., her aunt Olivia's husband.
At dawn, Lillian confirms she long suspected J.D. When Ellie announced her pregnancy, Lillian tried to arrange for Olivia and J.D. to raise the baby, but Ellie, defiant and about to name J.D., was thrown out before she could speak. Lillian acknowledges she should have expelled J.D. instead and that bringing Sawyer back was her attempt at amends after 18 years. Sawyer, despite everything, chooses to stay, honoring her contract and the bonds she has built, and determined to discover what became of Ana and her baby.