Jill Newman, a senior on a STEM scholarship at Gold Coast Prep, an elite private school on Long Island, begins her final year haunted by the death of her best friend, Shaila Arnold. Three years earlier, Shaila died during a hazing ritual, and her boyfriend, Graham Calloway, confessed to the crime. Jill is a member of the Players, a secretive social group at Gold Coast whose members endure a year of escalating challenges called "pops" to earn access to the Player Files, an encrypted app containing exam answers, college admissions contacts, and study guides passed down through generations. The Files are critical for Jill, who must maintain a 93 average to keep her scholarship, a fact she hides from her wealthy peers.
On the first day of school, the six senior Players attend the annual memorial assembly for Shaila: Jill; her best friend Nikki Wu, the ambitious daughter of Hong Kong textile magnates who serves as class president and Toastmaster, the Players' leader; Henry Barnes, Jill's boyfriend and an aspiring journalist; Quentin, a red-haired artist raised by his novelist mother; Robert, a brash former Manhattan kid; and Marla, a driven field hockey star. They occupy the coveted center table in the cafeteria, a symbol of their status atop the school's social hierarchy.
Jill's private life is entangled with Adam Miller, a former senior Player now at Brown University. In flashbacks, she recounts how Adam began tutoring her younger brother Jared in English during her freshman year. Over Friday-evening sessions, Jill and Adam developed an intimate friendship on her family's back deck, stargazing and sharing secrets. She fell for him, but Adam was dating Rachel Calloway, Graham's older sister. When Henry asked Jill out the previous summer, she agreed partly because Adam was away at college and Henry was present and willing.
At Nikki's back-to-school party, Jill receives anonymous texts: "Graham didn't kill Shaila. He's innocent." The sender identifies herself as Rachel. When Jill meets Adam at their usual diner, he dismisses Rachel's claims and urges Jill to leave the past alone. A newspaper article soon reveals Graham has withdrawn his confession and is seeking a new trial. The Players unanimously refuse to engage, but alone that night, Jill texts Rachel: "Let's talk."
The seniors select a new class of freshman Players, including Jared and Adam's younger brother Bryce. Jill consents to Jared's inclusion only after extracting a promise from Nikki that this year's hazing will be gentler. She shows Jared the Player Files for the first time, hoping the academic resources will help him recover from a failing biology grade.
Jill visits Rachel's tiny East Village apartment, where Rachel presents a critical finding: all the blood on Graham's shirt the night of Shaila's death was his own, from a deep cut to his stomach. None of it was Shaila's. The Gold Coast police, unprepared for a murder case, accepted Graham's coerced confession without testing evidence. Graham's parents arranged a private settlement with the Arnolds, and Graham was sent to Danbury Juvenile Center, a facility for wealthy juvenile offenders, without a trial. Rachel asks Jill to help investigate, but Jill leaves without committing.
As the semester unfolds, Jill grows disillusioned with the Players. When Nikki escalates a hazing event called the Show by forcing freshmen to physically act out scripted sex scenes, Jill is horrified to watch her brother participate. The breaking point comes during Road Rally, an all-night scavenger hunt. Reviewing photos afterward, Jill finds images of Jared kissing Marla and a terrified freshman girl forced into a same-sex kiss while Jared laughs nearby. Jill erupts, declares the Players "all bullshit," announces she quits, and walks away. She breaks up with Henry, and Nikki changes the password to the Player Files, locking Jill out. Without the study guides, Jill fails an English test for the first time. She is isolated from every friend.
Jill drives with Rachel to visit Graham at Danbury. He insists on his innocence, describing how police questioned him for hours without a lawyer. He also reveals that before initiation night, he discovered Shaila was cheating on him by reading texts on her phone from an unrecognized number, but he never confronted her because doing so would have given him a motive for murder.
Searching for Shaila's secret lover, Jill sneaks into the Arnolds' vacant house and finds a letter Shaila wrote to Kara Sullivan, her childhood friend from Manhattan. In it, Shaila describes being in love with someone older who warned that exposure would bring "life-ruining trouble." The affair began "in the parking lot behind the theater," which Jill and Rachel realize is the staff lot. Suspicion falls on Mr. Beaumont, Jill's AP English teacher, who was the subject of a freshman-year rumor about being involved with a student. Rachel takes the letter to Graham's lawyers, and Beaumont is brought in for questioning, but he is quickly cleared with an airtight alibi. The investigation stalls.
Jill pours herself into studying for Brown's Women in Science and Engineering scholarship exam and completes it with confidence. She is then summoned to Headmaster Weingarten's office, where he threatens to expose her history of using the Player Files to cheat, and to scrutinize Jared's improved grades, unless she stops investigating. Jill breaks down in front of her parents that night. They reassure her that she does not have to be perfect and that State's honors program is a viable path.
The final revelation comes when Adam invites Jill to his childhood bedroom and kisses her for the first time. She pulls back, wanting the relationship to be real. While Adam steps out, Jill reads newly forwarded photos of Shaila's letters to Kara. One mentions Adam by name, describing how he and Shaila spent the previous summer together. Then Jill discovers a velvet jewelry box in Adam's nightstand containing two diamond stud earrings, the pair Kara identified as the gift that made Shaila want to end the affair. Jill realizes Adam was Shaila's secret lover and flees to Rachel's apartment.
Rachel devises a plan: Jill will confront Adam on the beach behind Nikki's house while wearing a hidden recorder, with Rachel concealed nearby wearing one as well. Nikki will monitor the audio from inside and call police. On the last Friday of senior year, Jill lures Adam to the beach and presses him until he confesses. He describes how the affair began the previous summer and became physical during rehearsals for the school musical
Rent, how Shaila tried to end things after he gave her the earrings, and how on initiation night he assigned her the terrifying Ocean Cliff jump as her final challenge, hoping to be alone with her. When Shaila rejected him again, he shoved her into rocks, killing her. He then found Graham wandering nearby in a blackout and already covered in his own blood and directed him toward the body before calling police to frame him. Adam attacks Rachel when she emerges from hiding, then strikes Jill unconscious. Nikki, listening through the receiver, calls police and sprints to the beach with a field hockey stick, knocking Adam out.
Jill wakes in the hospital. Rachel has survived with broken ribs. Adam is arrested, and Graham will be released. A thick envelope from Brown arrives, but Jill tells her parents she is choosing State's honors program; she no longer wants to inhabit Adam's world.
On the final night, the student body gathers at Nikki's beach for a bonfire. Nikki holds the Toastmaster binder above her head and hurls it into the flames, declaring the Players finished. Rachel's girlfriend, a coder, has permanently deleted the Files app. The Players are dissolved. Jill stands at the water's edge with Nikki, Quentin, Henry, Marla, and Robert, looking up at a sky full of stars as a shooting star streaks overhead and disappears.