Apartment

Sejin (Ko Soo-young) lives alone in a high-rise luxury apartment. Late one night, while she was dragging her tired body to wait for the train at the subway station, a mysterious woman suddenly grabbed her and tried to jump off the rails together. After the shock, the woman died. Coupled with conflicts with her partners at work over how to decorate the windows for the upcoming Christmas, she began to be tortured by nightmares every night. What I can barely call happy is meeting Rouyan (Jang Xizhen), a disabled girl who lives in the apartment opposite, during a morning jog one day. Rouyan said that although her parents were both dead, they had relied on kind-hearted neighbors to take care of them and live happily. At the end of the conversation, she was given a Rubik's Cube. Shizhen noticed something strange in the room where Rouyan lived, and then used a telescope to observe night after night, and found that every time the time reached 9:56, the lights in the entire apartment would be turned off, and a body would be dragged out early the next morning. Sejin's behavior was discovered by a female high school student (Park Ha Sun) and she informed her mother, who called the police, but Sejin did not take the police's warning seriously. Soon, the female high school student took the initiative to apologize to Shizhen, and the two became friends. However, she repeatedly failed to solve the Rubik's Cube, causing Shizhen to take a breath when she discovered the secrets related to Rouyan hidden in it.