Clara Simmons, a bright high school senior, lives in a foster home with her mother, another girl, and an abusive foster father. She has earned a conditional scholarship to Yale and has been receiving steady support from a dedicated English teacher who helps her prepare for university. As a new school day begins, the class learns that their teacher has died by suicide, and a replacement, Mr. Heller, arrives with a magnetic presence and a gleaming smile. He seems sincerely interested in helping students, and he immediately recognizes Clara’s sharp mind, offering to assist her in continuing the Yale prep that could change her life. She accepts, hoping for the mentorship she’s long sought.
At first, Heller appears to be the perfect guide: he praises Clara’s writing, gives her extra attention, and treats her as an intellectual equal. But almost from the start, his behavior shifts from supportive to unsettling. His interest starts to feel personal rather than academic, and he begins to manipulate her, quietly isolating her from classmates and trusted adults, and pushing her to meet increasingly brutal writing deadlines. The line between mentorship and control blurs as Clara’s world tightens around him.
A defining moment arrives when Clara and her only friend, Zach, stumble upon the dead body of a girl in a park and report it to the police. This discovery anchors a growing sense that danger lurks behind Heller’s composed veneer. The tension escalates when Heller insists Clara stay overnight at school to rewrite her assignment multiple times after failing to meet his exacting standards—demanding that she recount her friendship with Zach and exposing vulnerabilities she’d rather keep private. The school counselor notices Clara walking home alone before school and vows to report Heller’s troubling behavior, a hint that authority may finally take notice.
That same day, Heller visits Clara’s home under the pretense of concern for her wellbeing, issuing veiled threats when her mother steps away to pour a drink. The scene shifts to Heller at home, speaking on the phone with his mother about an unavailable wife, while the footage shows him secretly drawing a birthday card—an eerie glimpse into a double life that contrasts with his outward charm.
As strange events begin to accumulate—terrifying coincidences at the school, odd disturbances in Clara’s life, and her foster father returning home bruised after a heated argument—Clara’s sense of safety erodes. The school counselor disappears under mysterious circumstances, amplifying the sense that something is deeply wrong. A house party becomes a turning point: Clara, Zach, and another classmate, Maddy, experiment with recreational drugs, and the night becomes a deeper investigation into the man who has assumed the role of mentor.
Driven to uncover the truth, Clara digs into Heller’s past and discovers a chilling pattern. At every school he has worked at, gifted female students vanish or die under suspicious circumstances. He has repeatedly reinvented himself, moving from school to school, selecting brilliant young women, gaining their trust, and eliminating anyone who might expose him.
Personal consequences unfold at home when Clara’s abusive foster father tears up her writing in a confrontation over welfare deception, and she returns to find him seemingly dead by suicide. The truth about Heller’s predatory pattern shifts the power balance: he rejects Clara and shifts his attention to a classmate, Maddy, who becomes his new favorite.
Clara’s resolve hardens as she contemplates exposing him. In a brutal turn, Heller reveals a secret video showing Clara using drugs with Zach and Maddy at the party. They lure Maddy into meeting to confront her about the footage, and she reveals that Heller forced her to record them secretly.
A dangerous confrontation follows: Clara and Zach break into Heller’s home and uncover evidence tying him to the park murder and other troubling events. Heller returns home with an unconscious Maddy, discovers the intruders, and ties them up as Maddy is killed before their eyes. He then kills Zach and is prepared to kill Clara, who negotiates a chilling bargain—she will write something that proves she truly understands his motives. He relents long enough for her to draft it, and when he reads her words, he is moved to tears. He allows her to leave, but Clara grabs a baseball bat and ends him.
The aftermath leaves the police clearing Clara of self-defense, allowing her to return to school. Yet the experience leaves an indelible scar; when class resumes, a new male teacher introduces himself, and Clara is haunted by flashbacks of Heller, briefly seeing his face in place of the new instructor. The film closes on a note of lasting unease, with Clara navigating the line between resilience and trauma as she steps back into the routine of school life.
