If You Tell a Lie

The novel opens with a cryptic prologue in which an unnamed narrator reflects on childhood sexual abuse, the speed with which lives can be destroyed, and the act of killing, all measured in seven-second intervals.

The story alternates between two timelines. In the present day, four women in their early forties receive threatening note cards reading "I KNOW WHAT YOU DID THAT SUMMER AND I'M GOING TO MAKE YOU PAY," echoing the 1997 slasher film I Know What You Did Last Summer. All four were cabinmates at Camp Pendleton, a summer camp for gifted children, for nine consecutive summers beginning at age eight. After a catastrophic final summer in 1998, they swore never to speak about what happened and cut all contact. Grace, a social media influencer in Miami, suspects a connection between the letters and the recent parole of Regina Crosby, whose husband was the camp's tennis coach. Blakely, the group's natural leader, initiates a group text insisting they meet at her Atlanta home.

The 1998 flashback introduces the girls arriving for their senior summer as seventeen-year-olds. Blakely, whose mother died during childbirth, is the daughter of a wealthy donor whose money affords special treatment at camp. Thera, a brilliant scientist who lost her mother to breast cancer at seven, shares an intense bond with Blakely rooted in mutual grief. Meg, a shy scholarship student raised by a single mother, is secretly coming to terms with the fact that she is gay. Grace has a rare genetic mutation causing severe weight issues and arrives harboring a secret: She recently caught her mother kissing her yoga instructor. During an earlier summer, the four sealed a blood oath of eternal loyalty and secrecy, a bond Blakely later exploits.

Blakely becomes fixated on Mr. Crosby (Jared), the camp's new tennis coach, a handsome married man with infant twin sons. Despite learning he has a wife, Blakely announces she intends to lose her virginity to him. Her obsession deepens when Mr. Crosby pays more attention to Meg during tennis, as Meg proves to be a natural player. Meanwhile, Blakely secretly has bulimia, bingeing on hidden food and purging in the camp bathrooms.

Blakely recruits Meg to accompany her into Mr. Crosby's office at night while Thera and Grace stand watch. When Blakely tries to sit on his lap, he flings her off and screams at her to leave. Meg snaps a Polaroid at the exact moment of the attempted straddle, creating a photo that misleadingly appears to show Mr. Crosby reaching under Blakely's skirt. Though Meg wants to destroy the photo, Blakely shows it to boys from another cabin, who steal it and tape it to Mr. Crosby's office computer. A staff member discovers the image, and the dean launches an investigation.

The dean pressures Meg with leading questions, framing her as a confused victim of abuse. Six additional girls come forward with fabricated allegations. The accusations spiral out of control: Mr. Crosby is fired, police search his home, and parents pull their children from camp. Mr. Crosby's wife Regina, who was sexually abused by a gymnastics coach as a child, immediately believes the accusations, and the revelation triggers a psychological crisis that merges her past trauma with the present.

When Mr. Crosby returns to campus to clean out his office, Blakely insists the girls intercept him so she can apologize. Blakely barges into his office while Meg watches from outside. Regina arrives through a back entrance carrying a knife and attacks Mr. Crosby in a violent frenzy, stabbing him repeatedly. Blakely wrestles the knife away. In a moment witnessed only by Meg, Blakely pulls down Mr. Crosby's pants and severs his genitals. The girls flee to the bathroom covered in blood. Blakely orders them to forget what happened, never speak of it, and never contact each other again.

In the present-day timeline, the women gather at Blakely's Atlanta home. Before Grace arrives, Blakely pulls Thera aside and claims her husband Phillip is abusive and controlling. She says Phillip killed her dog Camille, leaving the dead animal on her pillow with a note threatening to kill her other dog if she tried to escape. Once all four are together, Blakely reveals that she sent the threatening letters herself. Grace and Meg are furious. Blakely tearfully explains she had no other way to gather them and then reveals that Phillip is dead, that she killed him by cooking rat poison into his meatloaf. Grace storms out, refusing to be implicated in another crime.

After Grace leaves, Blakely apologizes to Meg for the lie that destroyed Mr. Crosby's life, taking full responsibility. This confession provides Meg with profound relief and convinces her to help. Blakely asks Meg and Thera to dispose of what she says is Phillip's dismembered body. She gives each a suitcase with body parts and handwritten maps. Meg drives to Lake Lanier with a weighted suitcase designed to sink. Thera drives to the Okefenokee Swamp, where alligators will consume the remains.

Weeks later, detectives visit Grace, informing her that Regina has been missing since shortly after her parole. They show Grace a letter Regina left for her mother naming Blakely as the girl who started everything and referencing a confession letter Meg had written to Regina in prison. In that letter, Meg confessed that Mr. Crosby never touched any of the girls, that the photo was misleading, and that every accuser fabricated her story. Grace confronts Meg, who confirms she wrote the letter out of guilt a year earlier but insists she knows nothing about Regina's disappearance.

Grace drives to Atlanta and finds Blakely's house listed for sale and already emptied. The listing predates the fake threatening letters by over a week. The real estate agent mentions speaking with Phillip the previous day. Grace checks Blakely's Instagram and finds a photo from that morning showing Blakely and Phillip together on a sailboat. The realization hits: Phillip is alive. The body Meg and Thera disposed of was not his.

Police arrest Meg at her Seattle home in front of her wife, Claire, for the murder of Thomas Reynolds, Blakely's father. Traffic cameras captured Meg driving Thomas's car near Lake Lanier, and investigators found his blood and teeth inside the vehicle. Meg realizes Blakely gave her Thomas's car, not a rental, and that the body parts she carried belonged to Blakely's own father.

The final chapter, told from Blakely's perspective aboard a sailboat with Phillip, reveals the full truth. She was never abused by Phillip. After her parole, Regina had sent Blakely letters demanding $300,000 for her mother's surgery. When Blakely refuses, Regina poisons Camille. When Blakely finally lets Regina into her house, a confrontation turns violent: Blakely grabs Regina by the ponytail, causing her to fall and crack her head on the marble floor, then suffocates her with duct tape. Phillip comes home, sees the body, and takes charge. His business was failing, he had been embezzling from Blakely's father, and Thomas was turning against him. Together they decide to kill Thomas, dismember him, and use Meg and Thera as unwitting accomplices, framing them for the murder. Blakely reflects that killing Regina satisfied a hunger that had driven her lifelong eating disorder and recalls that she mutilated Mr. Crosby that summer not out of trauma but out of rage at his rejection. She and Phillip sail toward a new life while Meg faces arrest, Thera is implicated, and Regina's body has vanished.