A year before the novel opens, five teenagers in a small rural town were killed during the week leading up to Halloween by Jackson Whitmore, a reclusive scrapyard owner. Jackson was arrested on Halloween morning and is now serving a life sentence in federal prison. A bronze phoenix memorial bearing the victims' names stands in the town square.
Penny Langley, a 17-year-old straight-A student and pianist, was dating Jackson's son Nash Whitmore at the time of the murders. Under pressure from her parents and the community, Penny cut off contact with Nash, who, along with his older sister Grace, has been shunned by the entire town. As the anniversary approaches, Penny stands at the memorial, drafting and deleting messages to Nash. Over breakfast with her best friend Adeline (Adi), Penny confesses she still thinks about him, but Adi warns her to move on.
That morning, Penny and Adi visit Party Town, a local costume shop, where Penny discovers the body of Noah, a classmate, with apparent stab wounds. Outside, Adi suggests Nash or Grace could be responsible, but Penny refuses to believe it. Across the street, she spots Nash watching before he retreats. Penny sends him a text, her first contact in months.
Penny drives to the Whitmore farm. Nash greets her at the door, hostile and hardened by isolation. He assumes she thinks he is the killer, but she insists she came because she cares. In the driveway, she notices a new red Chevy truck that Nash attributes to Grace, though Penny senses he is lying. That evening, Nash texts declaring his innocence and asks her to meet at midnight at Benji's, an old abandoned movie theater. Before they can meet, Nash is taken to the police station after someone reports seeing him near the costume store. While Penny waits outside, the red truck speeds past with a driver who bears a striking resemblance to Jackson. When Nash emerges, Penny drives him home, and he agrees to keep their midnight plan.
Penny sneaks out that night. On the way, she sees a hooded figure wearing a plain white mask identical to the one Jackson wore during the murders. Nash never shows. Her friend Zayn, who tracked her phone, picks her up and reveals he has been in regular contact with Nash for months. The next day, Karter, a classmate, is arrested for Noah's murder, and the town is relieved. Penny and her friends explore Benji's and determine the noise she heard inside was a collapsing shelf. At a Scream Fest horror event that Monday, Penny spots the white mask among costumed actors at least three times, but no one else notices.
On Tuesday, Penny shoves Ruby, a classmate who has been posting cruel videos about Nash, after overhearing her insult him at school. Later, Penny runs into Nash in a corn maze at the pumpkin patch. He explains that police arrived at his door the moment he was leaving to meet her, responding to a false report. He assumes Penny made the call, which is why he never came. They reconcile. That afternoon, Penny discovers Ruby's body at the pumpkin patch, confirming a copycat killer is at work since Karter was still in custody.
The FBI returns, led by Agent Rosenthal, who urges residents to stay in groups. Rosenthal questions Penny, who discloses her contact with Nash and the mask sightings. Adi mentions that Zayn left her house abruptly the night Penny snuck out, leading Penny to wonder if Zayn tipped off the police about Nash.
Penny invites Nash to a
Scream movie marathon at the cinema, reuniting the old friend group: Penny, Nash, Adi, Omar, and Zayn. During the screening, Mae Winstone, a kind classmate friendly to the Whitmores, is found murdered in the bathroom. The killing takes place at a location Jackson never targeted, confirming the copycat has abandoned his pattern.
The next day, Penny walks through a cornfield toward Nash's farm and is chased by the masked killer. She collapses at his property from exhaustion. When she presses Nash about the red truck's driver, he admits the man is Jensen, his uncle and Jackson's older brother, whose existence Jackson concealed from his children. Jensen found Nash and Grace earlier that year. As Nash drives Penny back to school, they spot the masked figure entering Benji's and call the police anonymously.
Later that night, Penny drives to Nash's farm after Grace goes missing. Grace returns safely, having been with her boyfriend Brant. As Penny drives home before dawn, a car slams into hers at a crossroads, flipping her vehicle into a ditch. The masked killer approaches, but Penny escapes on foot before collapsing from a concussion. She wakes in the hospital with a broken wrist. Nash and Grace, who heard the crash and rushed to help, are taken to the station for statements. Penny pressures Nash into calling Jackson in prison to verify Jensen's story. Jackson confirms he has not spoken to Jensen in years. Nash leaves the hospital furious.
On Friday, a memorial for the victims is held. Nash and Grace attend publicly, and Penny's parents allow Nash to stand with them. Afterward, in the church, the group discovers Billy Ross, Adi's crush, stabbed to death behind the pews. The killer cuts the power, sets the church on fire, and appears in the smoke wearing the white mask. Nash leads Penny to safety through a fire exit. Everyone survives, but the killer escapes.
On Devil's Night, October 30, Penny receives a photo of Adi unconscious in a car, hands bound, with the message "See you at the party." She grabs a kitchen knife, evades the FBI agents outside, and runs to the home of Sarah, a classmate whose absentee parents make her house a habitual party venue, where a party was planned. The house is dark and empty, but inside she finds Nash, groggy from being knocked unconscious and transported there. In another room, "BENJI'S" is scrawled in blood on a mirror. At the theater, they find Jensen freshly stabbed and dead. Zayn arrives, and together they locate Adi behind a movie screen, bound and gagged but alive. Nash notes the bindings in the photo appeared loose.
Grace appears holding a knife and calmly confesses she orchestrated everything. Omar, their longtime friend, steps out behind them with a bloodied knife, revealing he carried out all the murders at Grace's direction. The two have been in a secret relationship for over two years. Grace has harbored violent impulses her entire life, fueled by resentment toward the town. The killings this year begin because Penny keeps reconnecting with Nash. Grace reveals the full truth: She and Omar committed all five original murders the previous Halloween, not Jackson. Jackson discovered his daughter's involvement and, to protect her, planted his own hair on a victim and allowed the FBI to arrest him. Nash is shattered; he has spent a year hating his innocent father.
Grace orders Omar to kill the others. Omar stabs Adi in the abdomen. Penny silently activates an emergency 911 call while her phone's recording app captures the confession. Nash offers Grace a deal: She and Omar can flee in exchange for silence. Omar agrees, but Grace stabs him three times, killing him, her first murder by her own hand. She charges Nash and plunges her knife into his abdomen. As Zayn picks up Omar's dropped knife, the wounded Nash pulls a gun from Omar's pocket. When Grace lunges at Zayn, Nash fires. The novel ends on this gunshot—its final word "Bang"—leaving the fates of Grace and the other survivors unresolved in a deliberate cliffhanger.