Park Jimin committed suicide. He left tapes for 13 people who are responsible for his death. Rules are simple: Listen and send tapes to the next person. Mina, who was in love with Jimin, is next. Is she really one of those people? What did she, and others, do? If someone breaks the rules, original tapes are going to be leaked to the public. Who is keeping the original tapes hidden? How is this story going to end?