In the rain-drenched year of 2014, a man stumbles into a cozy eatery, his gaze fixed on the steaming bowl of beef noodle soup before him. As he sips, the strains of Claire De Lune gently caress the air, a soothing melody that accompanies him as he becomes acquainted with the eatery's second-generation owner.
Later that day, news reports flicker across screens, detailing a chilling series of murders that have shaken the city in recent months. The reports culminate in a revelation: Li Jen-yao, the serial killer known as "The Rainstorm Killer," has turned himself in and confessed to the gruesome deeds, including the murder of his own father.
Fast-forward to 2023, Chou Pin-yu awakens from a nightmare, her heart pounding as she is chased through the lush forest on a rainy day. The catalyst for this terrifying vision? A sleepless night spent poring over materials on the Rainstorm Killer.
As she makes her way to work, Chou Pin-yu encounters two elderly women who reside in the same apartment building. Their whispered tales of a haunting presence in her newly rented apartment, where the previous owner met an untimely end on a mountainous trail, send shivers down her spine.
Arriving at the We Film Studio, Pin-yu dives into her research on haunted houses, her mind already on her next assignment: an interview with Li Jen-yao, a task that the director, Hsu Ta-wei, has insisted she focus on. But as she prepares to leave for the interview, her colleague's stern reminder of Ta-wei's quarantine order leaves her with no choice but to venture alone to the prison where Jen-yao is incarcerated.
As Pin-yu steps into the bleak confines of the prison, her nerves fray at the sight of Jen-yao. Yet, surprisingly, he manages to calm her jittery nerves. In that moment of eye contact, an unexplainable sense of familiarity envelops her, as if they were destined to meet under these dark circumstances.
Pin-yu delicately explained to Jen-yao that Ta-wei was keen on crafting a documentary centered around his life and the heinous murders he had committed. Surprisingly, Jen-yao readily agreed to participate in the documentary, prompting Pin-yu to inquire about the reason behind his sudden acceptance. However, their conversation was abruptly cut short before Jen-yao could utter a word.
Following the prison visit, Pin-yu made a stop at a bar to collect her cousin Yun-chen. At the mention of Jen-yao's name, Yun-chen displayed an inexplicable expression that lingered on his face as they made their way to Pin-yu's apartment. On their way in, they encountered a couple who mistakenly took Pin-yu for their daughter, Chian Hsiao-tung. The wife rushed over with a bag of fruits, while the husband apologized profusely. Yun-chen's expression remained enigmatic as they continued their journey.
Later that evening, as Pin-yu penned a report on her meeting with Jen-yao, her thoughts wandered to his face. She shook her head, as if to dispel the image, and reached for a sip of water. Her cup was empty, so she made her way to the table to refill it. As she listened to the sound of raindrops and opened the window to check, a disc of Claire De Luna sat on the table, evoking memories of her and Ji-yen embracing on the bed. Suddenly, she heard a voice calling out for Hsiao-tung, jolting her from her reverie. It turned out that she had been indulging in a sexual dream with Jen-yao.
Pin-yu hurried to the bathroom to compose herself. She washed her face and gazed into the mirror, only to be confronted by the face of a sorrowful girl in a school uniform. Pin-yu let out a scream and ran from the bathroom, bringing Yun-chen along to witness the apparition in the mirror, only to find it had vanished into thin air.
With a firm belief that the apartment is haunted, Pin-yu, accompanied by Ta-wei, calls the landlady the next day after their first interview with Jen-yao at the prison. The landlady reassures them that there is nothing amiss with her apartment and if Pin-yu desires to leave, she will have to forgo the deposit. As they set up inside, the group commences their interview with Jen-yao. Ta-wei endeavors to elicit stories from Jen-yao about his childhood and upbringing, but he is resistant to sharing his past. When pressed about his high school and whether he had any friends, Ji-wei interjects that he did not have any.
Ta-wei then produces a yearbook and shows Jen-yao several of his classmates, all of whom were among the victims he had murdered. Despite Ta-wei's probing questions about the murders and what transpired, Jen-yao remains unresponsive except for when Pin-yu asks why he killed his classmates. In response, he mutters that he hated rainy days. Frustrated and enraged after the first interview, Ta-wei ventures outside to shoot footage for the documentary during the rain, with Pin-yu holding an umbrella for him. As they walk, Pin-yu hears a loud sound resembling a school bell, followed by the voices of someone discussing a deal where the three of them would go somewhere again.
Pin-yu looks around and spots the girl in uniform again in the distance under the rain. She shows Ta-wei, but he does not see anyone. Meanwhile, at an unknown house, a girl slowly opens the door to reach out for the food and cakes left outside by a man who had just arrived home. The same girl in a school uniform appears at the door, causing the girl to scream and shout that she had nothing to do with what had happened. The parents in the living room turn up the TV volume as the girl continues to scream at the girl in uniform, reassuring her it was not her fault. The girl in uniform leans on her shoulder as she continues to scream into the night.
Elsewhere, the enigmatic couple's other half, the lady burdened with amnesia, steps through the threshold of her home. She informs Hsiao-tung, someone she refers to as a confidant, of her intention to cook for him. The husband, as he goes to close an ajar window in one of the rooms, pauses mid-stride, tears streaming down his face upon witnessing a photograph of a girl in a ballet uniform on the table. The girl's image mirrors the one Pin-yu had seen, dressed in a school uniform. There's another picture of the girl and Jen-yao too. As the episode draws to a close, Pin-yu is at home, perusing the footage captured by Ta-wei. She replays the moment where she pointed to the girl in the video, only to find that there is no one there. Pin-yu reaches out to Yun-chen to share her discovery about the girl's reappearance, only for the girl to materialize before her and inquire if Pin-yu has been searching for her.
