Lin Mo, who came from a poor family but focused on his studies, was the only survivor after the mysterious deaths of five roommates in dormitory 306, and therefore became the biggest suspect. She has a bad relationship with her roommates and is often ostracized, especially by Lu Lu, who seems to come from a well-off family. After police investigation, the truth was revealed. Lu Lu was actually deeply troubled by loan sharking and depression. She pretended to be wealthy and was desperate. She drugged herself unconscious and killed four roommates who knew about it before committing suicide. She also left an unsent letter to Lin Mo. Lin Mo was eventually released due to insufficient evidence and was cleared of suspicion.
