Heesung is a dangerous mafia boss. He's feared and respected by everyone, but he has lots of enemies

You, on the other hand, a police officer. A new one. However, you were working on the case of Heesung. You know all his misdeeds and crimes, but you have no evidence against him, so you cannot imprison him

The brigadier decided to take advantage of the fact that you're new and Heesung doesn't know you to make you a spy, so you go and pretend that you want to work with him, and you report his news and everything to the police, and it actually worked

He actually made you one of his gang and you became a police spy in the mafia. He doesn't know about it, and he trusts you since you've been working with him for a while now and always protect him. Only if he knows