In-soo Kang Ha-neul is a high school student who lives with a rare gift: he can see ghosts. This ability, though fascinating to him, makes him a frequent target of ridicule and disbelief from his classmates, who dismiss his stories as fantasies. The tension around his gift spikes one night on a subway when a lingering spirit, a woman with a relentless grudge, confronts him and presses him to help her settle unfinished business. Despite fear, In-soo follows the haunting lead and eventually helps the authorities locate the body, a discovery that shatters the woman’s grieving family and deepens the guilt that haunts him.
Seeking a fresh start, he reaches out to his uncle Kim Jung-tae Sun-ll and tells him he intends to move in and transfer to the hometown school. Sun-ll, who shares the same eerie talent and fears additional hauntings, is reluctant to open his door to another spirit magnet, but in the end he agrees to take In-soo in. The move marks a new layer to the haunting: a long ride on a bus toward his hometown, where In-soo spots the ghost of a high school girl sitting on a bench, their eyes meet, and he chooses to avert his gaze rather than engage.
Back in his new environment, In-soo enters his hometown school and soon meets classmates Hae-Chul [Park Doo-sik] and Hyun-Ji [Han Hye-rin]. The surface calm is short-lived: after class, Hae-Chul menacingly warns In-soo to stay out of what he calls the “ghost business,” signaling that the ghostly world can entangle anyone who stumbles into it. The danger escalates when Sung-Hee [Joo Ah-reum], one of their peers, is attacked and then goes missing, shrouding the school in fear and rumor.
As In-soo spends more time with the ghost girl he talks to—an eerie confidant who seems to hold the key to her own tragedy—he begins to unspool the layers of her story. He reveals that his gift first surfaced in elementary school, when a classmate named A-Young vanished; he somehow knew she was dead and led the police to her body. Her mother pressed him for the truth about her killer, and the ghost pointed to a teacher, though In-soo kept silent out of fear, a silence that has haunted him for years.
Meanwhile, Sun-ll grapples with his own spectral companion, a woman who refuses to leave and who keeps him company in quiet, unsettling ways. In-soo’s focus, however, remains with the teenage girl who haunts him, eager to uncover the truth of her past. As time passes, more of In-soo’s classmates vanish: Hae-Chul and Hyun-Ji begin to suspect that something terrible is at play, and In-soo’s sketches and conversations with Jung Se-hee slowly pull back the curtain on her identity and fate.
To uncover the truth, In-soo asks Hae-Chul whether he knew Jung Se-hee. Uneasily, Hae-Chul reveals that she had committed suicide, a revelation that unsettles the entire class. In-soo’s next move is bold: he asks the room for anyone who knew Jung Se-hee by name, sparking silence and a palpable sense that the rumor mill has grown dangerous and personal. After school, tensions flare as Hae-Chul and Hyun-Ji confront In-soo, and Hyun-Ji confides a troubling hypothesis: Jung Se-hee’s father might be involved in the disappearances. A photograph circulated among friends—showing a man being strangled by an unseen force—seems to corroborate her fear, widening the circle of suspects.
Their suspicion drives them to a warehouse where Jung Se-hee’s father is rumored to be. The trio’s nerves tighten as they hear eerie sounds and sense a malevolent presence before they confront Jung Se-hee’s ghost in the space. The father arrives and violence erupts, killing Hae-Chul and Hyun-Ji, and In-soo finds their bodies after the ordeal, along with Jung Se-hee’s corpse hidden away in a closet.
Struck by the escalating danger and determined to end the haunting, In-soo turns to his uncle for help and guidance. The next day, the school hosts a surprise assembly in the library, where the homeroom teacher is revealed to be possessed by a ghost. The possessed teacher threatens to slaughter them all unless Jung Se-hee’s death is acknowledged and resolved. The ghost’s demand traces back to a painful history of bullying: Jung Se-hee was tormented by her peers, with teachers, classmates, and even her own father failing to intervene. The ghost’s demand for retribution becomes a plan to unleash a deadly blaze, as gasoline is spread and a lighter is poised to ignite a catastrophic fire.
In a tense twist, the real ghost of Jung Se-hee appears and intervenes, catching the lighter to prevent an immediate disaster. Yet the haunting spirit remains, offering a chilling choice: surrender to revenge or find release. The ghost then possesses another student—the mute girl who carried guilt for not speaking up—and the classroom is plunged into chaos. In-soo acts quickly, tackling the possessed student and rushing to safety with his uncle close behind.
The uncle arranges an exorcism circle to end the two intertwined hauntings once and for all. In-soo speaks directly to Jung Se-hee, urging her to let go of the pain she carried for so long. With a decisive cue, his uncle signals the exorcism to commence, and a dagger is used to sever the lingering ties that tether Jung Se-hee to the living world. The ritual succeeds, Jung Se-hee’s torment is released, and she moves on, freeing herself from the scars of her suffering.
In the aftermath, the school pays tribute to Jung Se-hee with a memorial for the girl whose life was cut short by bullying and neglect. In-soo leaves behind a sketch of Jung Se-hee as a last offering and bids her farewell. Time passes, and the story follows In-soo into adulthood: now working as a teacher at the same school where it all began, he encounters another ghost—this time a teenage girl—before the screen fades to black, leaving the enduring sense that the haunting will continue to follow him in new forms.
