In the all-female world of Jookran High School for Girls, the atmosphere feels strict and shadowed by fear as a longtime homeroom teacher known to students as the “Old Fox” tightens her grip. Mrs. Park Lee Yong-nyeo, whose relentless methods leave a mark on every corner of the yearbooks and every student’s memory, quietly summons her new colleague Hur Eun-young Lee Mi-yeon and delivers a chilling warning: “Jin-ju, is definitely dead, but still attending school.” The line hangs in the air as a cruel twist of fate unfolds.
Shortly after, Mrs. Park’s body is found, strangled by an unseen hand. The discovery is made by three new senior students who will forever shape the school’s legend: Lim Ji-oh Kim Gyu-ri, a gifted artist who leans into superstition; Yoon Jae-yi Choi Kang-hee, a quiet, withdrawn outsider; and Kim Jung-sook Yoon Ji-hye, who often seems to be on the edge of being overlooked. Their surprise encounter with danger marks the beginning of a haunting cycle.
The class is then left under the thumb of a replacement teacher, the brutal Mr. Oh Park Yong-su, nicknamed “Mad Dog.” He is quick with punishment and unafraid to torment the class’s star pupil, Park So-young Park Jin-hee, fueling an atmosphere of fear and tension that seeps into every corridor and classroom.
Ji-oh’s response to the tragedy is to paint the fallen body, a decision that earns a severe punishment from Mr. Oh. Wounded by the events, Ji-oh finds solidarity with Jae-yi, a former artist herself, and the two begin painting together in a storage room rumored to be haunted. Ji-oh also learns that So-young uses the storeroom to hide her smoking habit, a detail that deepens the sense of secrecy that clings to the school.
Eun-young, ever watchful, grows suspicious that Ji-oh might be more than a living student—perhaps a ghost. The bells Ji-oh carries, gifts once given by Jin-ju, become a point of tension: Eun-young believes Ji-oh is a supernatural presence, while Ji-oh insists the bells were given by Jae-yi. In a cruel twist of fate, Mr. Oh is attacked by Jin-ju and dies by stabbing, an event that further blurs the line between memory and rumor.
As nights pass, Ji-oh encounters Jung-sook Yoon Ji-hye and So-young arguing, a clash that ends with So-young storming out. Jung-sook then takes her own life in a manner mirroring Mrs. Park’s death, a tragedy that intensifies the sense of a school haunted by past traumas.
So-young confides in Eun-young about her complicated bond with Jung-sook; the teachers’ rivalry and eventual drift, Jung-sook’s bitterness, and the loneliness that grew between them are revealed. While Ji-oh paints, she uncovers a bust that Eun-young created for Jin-ju, along with Mr. Oh’s corpse. A flashback reveals Jin-ju’s death in the storeroom while trying to save the statue—when the statue fell, the knives meant for sculpting shattered and claimed her life.
Eun-young pieces together yearbook clues: Jin-ju has returned to the school every three years as a false student, and she is currently posing as Jae-yi. The confrontation with Jin-ju is inevitable, but Ji-oh arrives in time to plead for an end to the bloodshed and a chance at peace. Jin-ju confesses that all she wanted was a normal high school life and to be loved fearlessly, a love Eun-young couldn’t provide. With a quiet promise to remember her and to mend the misgivings of the past, Jin-ju disappears, leaving blood on the walls and two exhausted girls in the haunted room, Ji-oh resting her head in Eun-young’s lap.
The next day, a student peeks in on them from the doorway, then leaves. When the girl turns, she is revealed to be Jung-sook’s ghost, a final, chilling reminder that the past lingers long after the living have moved on.
