Served as an undercover for several years, Leung Siu Tong or Laughing (Michael Tse) escaped from all calamity. Two years ago, he underwent special training, pretending to be mute and sneaked into an armed robbery gang as a spy. He successfully solved the criminal case and later became an instructor for special training in undercover work. Unfortunately he was unable to adapt to the stress in the discipline, so he applied to be an undercover once again. His supervisor Chief Inspector Jodie Chow Mong Ching (Fala Chen), looking exactly like his deceased girlfriend, was the person he communicates with during his undercover work. A female inspector and an undercover, falls into a black-white romance, and eventually became a pair that is in love, but cannot love…