Mingyu (Jang Hyuk) is a middle school teacher with a gentle, honest and kind personality. One day, when he bravely helped others to catch a thief, he was mistaken for a thief by Tong Zhen (Jeon Ji Hyun), a female police officer who was off duty. Tong Zhen then tortured him to extract a confession. When Mingyu was finally proven innocent, he had been beaten to a pulp by Tong Zhen. After recovering from his injuries, Mingyu was sent by the school to the red light district to counsel problem students. The police also arranged personnel to protect his safety. However, what Mingyu did not expect was that his guardian was Tong Zhen. The two people who were extremely jealous of each other began an awkward cooperation, and they gradually developed feelings in the process.