The novel unfolds across two intertwined timelines: one following seventeen-year-old Emily Vaughn in the small Delaware beach town of Longbill Beach during 1981–82, and another set in the present day as newly minted US Marshal Andrea Oliver arrives on her first assignment.
The story opens on prom night, April 17, 1982. Emily, nearly eighteen and seven months pregnant, defies her controlling, physically abusive father, Franklin Vaughn, and leaves the house barefoot in a turquoise prom dress. Her former teacher Dean Wexler intercepts her on the road, intimidating her into silence when she hints she knows something damaging about him. At the prom, Emily is dismissed by Clay (Clayton Morrow), the charismatic leader of her former friend group. Outside, Blake (Eric Blakely), another member of her former friend group, apologizes for previously telling her to terminate her pregnancy, but when he accidentally grabs her injured wrist, she falls. She screams that everything is his fault and stumbles into a dark alley. There, overcome with relief that her baby is unharmed, Emily feels a transformative surge of love for her unborn daughter. Then she sees black shoes and the arc of a bat swinging toward her.
The present-day narrative begins with Andrea Oliver graduating from the Federal Law Enforcement Training Center (FLETC) in Georgia as a deputy US Marshal. Her mother, Laura Oliver, opposes the career, and her father, Gordon Mitchell, supports Andrea without endorsing the choice. The tension stems from a revelation two years earlier: Andrea's biological father is Nicholas Harp, a convicted cult leader whose real name is Clayton Morrow. Laura entered Witness Security before Andrea was born to hide from Clay. After the ceremony, US Senator Jasper Queller, Laura's estranged older brother, arranges a private meeting alongside Inspector Michael Vargas, Andrea's Witness Security handler and ex-boyfriend. Jasper reveals that Clay faces a parole hearing in six months and proposes that Andrea take an assignment guarding Judge Esther Vaughn, Emily's mother, in Longbill Beach, where Clay grew up. Forty years earlier, a pregnant teenager named Emily Vaughn was beaten nearly to death. She survived long enough for her baby to be delivered, then died. Clay was the prime suspect, but the investigating officer's file ended with a frustrated notation: "MORROW KILLED HER. NO PROOF." If Andrea can prove Clay committed the murder, he stays in prison for life.
Andrea lies to Laura about being stationed in Oregon and travels to Longbill Beach, where she meets her partner, Deputy Leonard "Catfish" Bible, a scarred veteran Marshal. They guard the Vaughn estate on the night shift while death threats against the judge are investigated. Emily's former associates still live in town: Ricky Fontaine, Emily's former best friend and Blake's sister, runs the local diner; her ex-husband Nardo (Bernard Fontaine) works at an organic farm called Dean's Magic Beans, operated by Wexler. Andrea also meets Judith, Emily's forty-year-old daughter, a collage artist whose sharp features suggest she and Andrea may share a biological father.
Past-timeline chapters reveal how Emily's crisis began. Six months before the prom, Emily took LSD at a party with her clique: Clay, Nardo, Blake, and Ricky. She blacked out and woke the next morning with her dress inside out and her underwear missing. Weeks later, a doctor confirmed she was pregnant with no memory of the assault. Inspired by the TV detective Columbo, she interviewed each suspect, recording findings in a pocket-sized address book. Each confrontation followed the same pattern: initial friendliness, then fury, then contempt. Wexler choked her and claimed sterility. Ricky ended their friendship. Blake proposed a loveless marriage. Nardo deflected blame. Clay told her to accept the consequences. Emily also discovered that Clay and Jack "Cheese" Stilton, the police chief's son, were secretly in a sexual relationship; she witnessed Clay savagely beat Jack when Jack mentioned their plan to leave town together. Jack, who had conducted his own investigation, pieced together what likely happened on the night of the party: Blake gave Emily sedatives, and she was loaded into Wexler's car while nearly comatose. Jack promised Emily he would find her rapist.
In the present day, Andrea and Bible discover a dead young woman named Alice Poulsen, a farm volunteer, in a field at Wexler's farm. She is horrifyingly emaciated, with a silver ankle band permanently welded around her leg. More women emerge from the barn in identical yellow dresses, barefoot and skeletal, wearing similar bands. The farm operates as a cult, with Wexler controlling the women and Nardo recruiting them. Inside the farmhouse, Star Bonaire, one of the farm's controlled residents, uses Andrea's phone to photograph a word traced in flour on the counter: "Help." Andrea later interviews Melody Brickel, Star's mother and part of a network of parents whose children are trapped at the farm. Melody explains the critical connection: The girls are being starved into unconsciousness, rendering them incapable of awareness or consent during sexual assault, just as Emily was drugged into unconsciousness at the party forty years earlier.
A fire breaks out at the Vaughn estate from overloaded electrical fuses. Andrea and Judith remove flammable supplies from the studio before the structure collapses; an explosion throws both women into the swimming pool. At the hospital, Judge Esther summons Andrea and confesses a series of secrets. Franklin beat both her and Emily for years. Esther wrote the death threats to herself to trigger Marshal protection because Wexler had sent surveillance photos of Guinevere, Judith's teenage daughter, along with a farm volunteer application. Wexler claimed to be Judith's biological father after Emily's attack and blackmailed the Vaughns for decades. Franklin secretly recorded his negotiations with Wexler and Nardo over the years, and Esther hands Andrea a briefcase containing a laptop with those recordings and documents detailing land transfers, trust arrangements, and wire transactions.
The Marshals arrest Wexler, but Nardo evades the perimeter and drives to the diner. Andrea follows and relays a coded message through Laura to Mike, who alerts the team. Chief Jack Stilton, the boy who once promised Emily he would find her rapist, arrives drunk and demands that Nardo confess. Nardo graphically admits to raping Emily and suggests Wexler assaulted her as well. When Nardo reaches for his concealed handgun, Stilton fires, severing his carotid artery.
Bible and Andrea drive Ricky home. In open console drawers, Andrea finds Emily's address book containing the full "Columbo Investigation," with entries spanning October 1981 through prom day. The final entry records Ricky threatening to beat Emily to death. A receipt for a boys' tuxedo matches black fragments found on the murder weapon. Ricky, who has secretly swallowed handfuls of pills, confesses: She killed Emily in the alley after seeing her talking to Nardo. Her brother Blake advised her on concealing the crime, and together they burned Emily's dress and purse. Andrea forces Ricky to vomit the pills, refusing to let her die on her own terms.
One month later, Andrea has settled into a Baltimore apartment. Wexler has accepted a 25-year plea deal, and Ricky will spend the rest of her life in prison. Stilton's shooting of Nardo has been ruled justifiable. Andrea and Mike have resumed their relationship. Her phone rings with Bible's caller ID, but the voice belongs to Clayton Morrow on a contraband phone, inviting her to visit and dangling damaging information about Jasper. Andrea recognizes the manipulation: Clay needs attention the way fire needs oxygen. She ends the call without responding. Her mother once accused her of flinging herself over every cliff she encounters. Andrea reframes her life as a diving board. She has learned how to jump. She already knew how to fall.