SuperM are the strongest mafia in Seoul. Their greatest asset: the secrecy of their leader. Many believe it is either Taemin or Baekhyun, the eldest of the seven leading members. However, it's a completely different individual: Kang Seulgi is SuperM's precarious, dangerous boss. When young members Mark and Yeri are threatened, Seulgi must use her sly power to restore safety to those she cares about.