Shortly after graduating from college, policewoman Lin Yue was assigned to work undercover under the drug lord Li Qiang. However, during the undercover mission, she gained a warmth she had never felt before, met a group of people who were like family members, and fell in love with Li Qiang's son Li Lie, a doctor who had no knowledge of his father Li Qiang's criminal behavior. But as the undercover mission deepens, Lin Yue indirectly discovers that things are not as simple as they appear. In the end, Lin Yue fulfills his police duties and completes the mission brilliantly, but loses everyone he cares about... After the undercover mission ends, Lin Yue accidentally discovers that his father's negligence as an undercover agent led to the escape of the drug lord Caesar. In order to make up for his father's mistakes, Lin Yue began to arrest Caesar, but discovered that there was another truth to the incident that year...
