Tells the story of a judicial trainee named Kim Yo Han. After going undercover for an investigation, Kim Yo Han experiences a crisis and ends up struggling to try to obtain a hand of cards that will change his fate as he gambles in prison. Kim Yo Han is prudent and always thinking a few moves ahead, and he keeps a poker face on. The series revolves around a judicial trainee whose life turns upside down when he goes on an undercover investigation, and ends up struggling to try to recover his normal life.