Lin Xia, an 18-year-old freshman, checked into Dormitory 404, East Building 7, University of South China. From the moment she opened the dormitory door, strange events happened one after another - the face of a strange girl appeared in the mirror late at night, intermittent crying came from the closet, and a white dress that belonged to no one always appeared on the clothesline on the balcony. As roommates Su Xiao, Chen Yu, and Zhao Man were involved in the incident, they discovered that every supernatural phenomenon pointed to the past "disappearance case" in dormitory 404. The four people formed a temporary investigation team to search for clues in old files in the campus library, secret diaries in abandoned teaching buildings, and dusty medical records in the school hospital. Little did they know that they were walking step by step into a death trap woven by "obsession" and "lies", and a seemingly ordinary object in the dormitory was the key link between reality and weirdness.
