Fang Hui (Bai Baihe), a single and beautiful woman, works hard alone in a big city and lives a life of going from one place to another. One night, she suddenly heard someone outside the door violently pulling the door handle and trying to break in. Although she didn't see who was outside the door, she learned from the security guard Xiao Wu that the surveillance on her floor was broken. This suddenly shrouded Fang Hui's peaceful life of living alone in a shadow of fear and anxiety. When night fell again, Fang Hui, who was sleeping soundly, vaguely noticed that someone had entered her room, but she found no signs when she woke up. Gradually, her mental state began to get worse and worse. Several men who appeared repeatedly around her, including real estate agent Gao Qi, security guard Xiao Wu, company leader Mr. Li, and pet doctor Zheng Fei, all seemed to have their own ulterior motives. With the strange disappearance of her best friend Qiao Xiaoman, living alone has almost become Fang Hui's nightmare...