Zhang Yuanbai has been undercover for three years. On the night when the files were handed over, the security room was bombed and the only old police superintendent who knew his identity was transferred. When I woke up, I was in a sauna in Yuen Long, and my younger brother Luo Tianhong handed me the slip. He glanced at the numbers and paused. The boss behind this establishment was the one who sent him to the police academy.