Ted meets Lily at a Heathrow Airport bar and tells her about Miranda's affair with contractor Brad Daggett.

Lily explains her morality system to Ted, arguing that killing Miranda would rid the world of a harmful person.

Ted and Lily agree to meet at the Concord River Inn in one week if both still want to proceed with the murder.

Ted arrives at the Concord River Inn and Lily joins him; both formally commit to murdering Miranda.

Ted meets Brad for drinks and later sneaks back to steal a spare key from Brad's house.

Ted and Lily meet at the Old Hill Burying Ground cemetery to finalize their plan, and Ted kisses her.

Ted decides to pursue a divorce instead of murder, but Brad arrives at his Boston home armed with a gun.

Brad shoots and kills Ted inside his own Boston home.

Lily reads about Ted's murder in the newspaper and concludes Miranda arranged the killing.

Lily travels to Kennewick and blackmails Brad, threatening to expose him as Ted's killer unless he helps her.

Detective Kimball visits Lily at her home and questions her about her connection to Ted Severson.

Brad beats Miranda to death with a wrench at the Severson house while Lily watches.

Lily drugs Brad with chloral hydrate, then strangles him with a wire coat hanger in his truck.

Lily drives Brad's truck to Monk's House and dumps his body into the well in the meadow.

Lily stabs Detective Kimball in a cemetery and is immediately arrested by his partner Detective James.

Ted Severson meets Lily Kintner at Heathrow Airport and, after confiding about his wife Miranda's affair, is drawn into a plot to kill her. After formal planning and a growing romantic connection, Ted changes his mind and decides to simply divorce Miranda — but it is too late, as Miranda has already sent Brad to kill him. Lily learns of Ted's murder and shifts her focus to punishing Miranda, blackmailing Brad into helping her lure Miranda to the Severson house. Brad ultimately kills Miranda, and Lily then disposes of Brad by drugging and strangling him, hiding his body in a well. The police, led by Detective Kimball, grow suspicious of Lily, and her attempt to eliminate the investigator ends in her arrest in a cemetery. The novel closes with Lily seemingly avoiding prison time, only to receive a letter warning that bodies she hid long ago may soon be discovered.

The core murders and investigation driving the main story.

A painter named Chet arrives at Monk's House and makes young Lily feel unsafe whenever he watches her at the pool.

During a late-night party at Monk's House, Chet enters young Lily's room and molests her while she pretends to sleep.

Young Lily kills a feral cat that had attacked her pet Bess, discovering she is capable of deadly violence.

Lily packs Chet's belongings after murdering him and dumps everything into the well to conceal all evidence of his presence.

Lily's mother tells her that Chet left in the middle of the night, and Lily realizes she has gotten away with murder.

Lily meets Eric Washburn at Mather College, falls in love with him, and begins a relationship after he breaks up with Faith.

Lily spots Eric kissing Faith — now with dyed red hair — outside his New York office building in secret.

Ted visits Miranda at the Kennewick property, tours the unfinished house, and grows increasingly suspicious of her closeness with Brad.

Ted flashes back to assaulting Rebecca Rast after prom and realizes he does not want to commit another act of violence.

Miranda meets with Brad two days after Ted's murder and coaches him on the alibi story he should tell police.

Miranda drives to Brad's house at night and spots Lily Kintner meeting with him through the window.

Miranda recalls how she encouraged Eric to pursue her while Lily was still dating him, revealing her long habit of manipulation.

Miranda learns from Brad that Lily wants her dead and immediately proposes they lure Lily in and kill her instead.

Kimball shows the Kennewick Inn bartender a photo of Lily and confirms she stayed there the previous week.

Lily's attorney Stephanie tells Lily she likely won't serve any time because Kimball was acting outside police protocol.

Lily's troubled childhood at Monk's House, where a houseguest named Chet molested her, first awakened her capacity for violence and her need to protect herself by any means necessary. Her subsequent relationship with Eric Washburn at college ends when she discovers his long-running betrayal with his ex-girlfriend Faith, sharpening her resolve against those who deceive her. Meanwhile, Ted's own dark past — a violent act against a prom date — quietly shadows his decisions throughout the novel, even as he grows closer to Lily and suspects Miranda's true character. After Ted's murder, Miranda carefully manages the investigation, coaching Brad on his alibi and steering police attention toward Lily at the station. Behind the scenes, Kimball's methodical detective work traces Lily's movements to Kennewick, while Lily's attorney ultimately dismantles the case against her by exposing Kimball's obsessive and unauthorized conduct.

Backstories and investigations shaping the plot beneath the surface.

Lily lures Chet to an old well in the meadow, shoves him in, and drops rocks down to ensure he is dead.

Lily removes Eric's EpiPens from his luggage while he sleeps and hides them under her mattress.

Lily grinds cashews into Eric's chicken korma, carefully preparing a fatal trap using his severe nut allergy.

Eric rushes into Lily's room after eating the korma and Lily watches him die while pretending to search for his EpiPens.

A constable visits Lily's apartment and tells her that Eric's death has been officially ruled accidental.

Lily visits the pub, sees Eric's winning photo on the wall, and decides he will be her last murder victim.

Lily recalls a past encounter where Faith introduced herself as Miranda, revealed her engagement to Ted, and unknowingly triggered Lily's revenge plan.

Miranda realizes a Winslow parking ticket found among Ted's possessions may connect Lily Kintner to her late husband.

After Kimball leaves her home, Lily receives Brad's phone signal confirming the meeting with Miranda has been arranged.

At the police station, Miranda pretends to struggle to identify the suspect sketch before naming her contractor Brad Daggett.

Lily arrives at the dark, empty Severson house in black clothing and gloves and waits in silence for Miranda and Brad.

Miranda confronts Lily inside the house about Eric and Ted; Brad suddenly enters through the side door holding a large wrench.

Brad swings the wrench at Miranda instead of Lily, revealing he chose Lily's side and beating Miranda to death.

After dumping Brad's body in the well at Monk's House, Lily sees a vision of her younger self and silently promises her survival.

Lily reads her father's letter revealing the meadow behind Monk's House will be leveled by bulldozers, threatening to expose the hidden bodies.

Lily's childhood murder of Chet at the well in the meadow establishes the first and most formative act of her violent moral code, setting the pattern for every killing that follows. Her meticulously staged murder of Eric in London — a fatal allergic reaction engineered through hidden EpiPens and doctored food — reveals the chilling precision she brings to each act of revenge. A crucial flashback discloses that Lily's decision to target Miranda was triggered years earlier when Faith reintroduced herself as Miranda and confirmed she had always known about Eric's infidelity. As the story converges, both Lily and Miranda separately manipulate Brad into believing he is each woman's true ally, leaving the outcome of their confrontation at the Severson house suspended in fatal uncertainty. Brad ultimately chooses Lily's side and kills Miranda, but Lily's own survival is then threatened when Kimball closes in — a conflict that ends in violence, arrest, and an unsettling cliffhanger about the bodies buried in the well.