Jina, a top employee at a call center dedicated to a bank's credit card department, maintains a complex relationship with her boss. Despite her confident demeanor, her mental well-being has suffered significantly, making interactions with others increasingly difficult. This struggle is exacerbated by her father’s indifferent reaction to her mother’s death, and just recently, Jina had to renounce her inheritance during a lawyer’s meeting—revealing her mother's will had been altered only two years before. Isolating herself, Jina spends her days in solitude, consuming TV dramas and mukbang videos during her commutes or while dining alone.
One fateful evening, as she returns home from work, Jina encounters a woman pacing outside her apartment, agitated while speaking with police officers. When Jina questions her distress, the woman chastizes her for being oblivious to the previous noise, which was, shockingly, the sound of their neighbor’s tragic death underneath a pile of adult magazines. This revelation leaves Jina perplexed; she distinctly remembers the neighbor showcasing a matchstick trick just days after his alleged demise. That night, the unsettling truth is confirmed as she reads about the incident in an online article.
The following Monday, under orders from human resources, Jina is tasked with training a new employee named Sujin. Despite her reluctance, Jina accepts, aware that her struggle to engage in normal company dynamics may hinder their performance. Sujin's training proves challenging—her clumsiness and over-reliance on Jina are evident as she grapples with executing calls and responding to clients adequately.
Feeling increasingly frustrated, Jina finds herself distancing from Sujin, leading to Sujin's absence from work. Jina's boss hints at the likelihood of her returning, but acknowledges that Sujin's inability to pass her training is a critical barrier. Ultimately, Jina discards Sujin’s belongings into the office trash, a sign of her growing detachment.
Meanwhile, Jina discreetly monitors her father through a home camera installed at her childhood home. She observes him hosting church members, exhibiting odd behaviors in the aftermath of her mother’s passing—dining alone in his bathroom or attempting dance steps in the living area. Jina's life further intertwines with Seong-hun, a man with a broken leg, who plans to occupy the apartment of Jina's late neighbor after her tragic death prompted a decrease in rent.
Upon returning to her job, Jina’s emotions escalate, mirroring the stress Sujin exhibited earlier. A routine call from a demanding customer exacerbates her anxiety, culminating in a breakdown that prompts her to leave the office. In a fit of rage, she confronts her father during a phone call, demanding an apology for his treatment of her and her mother. He hangs up abruptly, leaving Jina feeling desolate as she waits for dusk near a streetlight.
Later, she discovers her new neighbor struggling with some interfering signals due to moving company mishaps. This irritates her enough to reach out to Seong-hun, requesting assistance with the issue.
In an effort to find solace, Jina requests a leave of absence from work and reaches out to Sujin, expressing remorse for her harshness, which brings Sujin to tears. As the evening unfolds, Jina witnesses Seong-hun and his family hosting a vigil for the former tenant. Though she stands at the doorway, she hesitates to join them. When Seong-hun steps outside to demonstrate the smoke trick previously shown by her neighbor, Jina’s connection to her past deepens, and the disturbance with her TV is resolved.
As Jina prepares to leave her workplace—uncertain if this means quitting or merely taking leave—she discusses her plans with her boss, who suggests dinner when she finds clarity. On the bus ride home, Jina receives a call from her father, who feigns ignorance about blocking her number. She informs him of the camera she set up in the living room, ready to keep a watchful eye on him from afar.
