Wu Yu, a new recruit at the Jinhai Public Security Bureau may seem like a timorous guy next door, and he doesn’t seem to care at all even when Captain Bu Chonghua, his supervisor, constantly looks for trouble because he thinks Wu Yu got the job through nepotism. What others don’t know is that behind Wu Yu’s gentle smile are scars from being undercover in a dangerous criminal gang. As Wu Yu gets involved in several seemingly related and troublesome cases, Bu Chonghua begins to change his view of him.