After losing both parents at a young age, Lai Yat Tsau becomes a parent figure for his three younger sisters. His mother’s death and his father’s fall to drug addiction turned Yat Tsau into a very quick-tempered and chauvinistic man. Originally assigned to the Kwun Tong Police Station, Yat Tsau’s superior transfers him to the K-9 unit to work with police dogs, hoping that the strict training would better shape his character.