A person living alone received a text message from an unknown number after ordering takeout late at night, warning "Don't open the door." Later, a person claiming to be a neighbor continued to send messages to remind the food delivery man outside the door that "there is a knife in the back." The next day, a girl who claimed to be a neighbor from 306 came to explain that she had witnessed a dangerous situation the night before and sent a text message to remind her. However, the protagonist finds that the source of the text message is suspicious, and the way the other party knows his mobile phone number is questionable. There was a strange noise outside the door that night. After calling the police the next day, they found that all text message records had mysteriously disappeared, and 305's neighbors still refused to open the door. The truth is shrouded in mystery and fear continues to spread.
