Jung Woo gets to work with Myung Ju. On his first day in Myung Ju's office, an old lady wearing shabby clothes comes to the office. He falls for the old lady's act, and that's when Myung Ju shows up to set things right. Meanwhile, Jong Hak is heavily stressed out from work and pressured by his colleagues and supervisor, and he ends up falling ill and being taken to the hospital.

Criminal Department 2 comes across an unexpected tip about a hidden gambling den in the mountains. They decide to send someone to the gambling den undercover, but the only person whose face is unfamiliar to the target is Myung Ju. However, she does not know a thing about gambling. Sun Woong and the team must turn Myung Ju into a gambler overnight.