The drama mainly tells the story of police officer Gao Jiasheng (played by Raymond Lam), who returned to the police station after successfully destroying a gang as an undercover police officer, PTU female sergeant Ho Huiling (played by Charlene Choi) and the iron-faced and selfless captain Liu Jianhui (played by Alex Fong). Although the three had misunderstandings, contradictions and conflicts in the PTU, they gradually established a true friendship with their colleagues and became real good policemen after performing their missions and facing the moment of life and death.