Bai Chengzhu (Sun Xianzhou), a middle-aged man with a successful career, lives in a high-end apartment with his wife Minzhi (Jeon Misun) and a pair of children, Sanhe and Xiuya. They have no worries about food and clothing, and are happy and comfortable. On this day, he unexpectedly received a call, and the other party said that Chengzhu's brother Chengze had been missing for several months and his whereabouts were unknown. Chengze ran away from home after high school, leaving a dishonorable record in his resume. Chengzhu, who had a secret in his heart, came to his brother's apartment and found that there were many other people's clothes in his room, and the surrounding residents were all pale at Chengze, and the doors of each house were marked with unknown signs. Not long after, a mysterious man wearing a motorcycle helmet attacked Minzhi and his son. The danger was obviously approaching Bai Chengzhu's family, and Chengzhu, who had a serious obsession with cleanliness, was almost mentally collapsed. In the luxurious and bright private house, a mysterious person quietly moved in and played a dangerous game of hide-and-seek with the owner...