Undercover Darling summary:

The daily life of Lee Jae, a hot-blooded police officer in a quiet rural village, is turned upside down by the reunion with his first love.Who would have thought that his first love, who had suddenly disappeared without a word one day, would reappear before him as a gangster?"Just bear with it a little longer. I'm going to do everything that I've been putting off today."Can he resist that dirty handsome face that he never wanted to see again?