Enduring the hardship of his father's drug addiction and his mother's death, hot-headed cop LAI YAT-CHOW (Bosco Wong) single-handedly raises his three younger sisters. Due to his domineering personality and short temper, he is transferred by his boss to the K-9 Unit to undergo a grueling training session together with a police dog, yet in the process, a misunderstanding causes him to have a bitter feud with MA CHI-HO (Linda Chung), a veterinarian for the Agriculture, Fisheries and Conservation Department (AFCD) and the police. Surprisingly, CHI-HO takes the initiative to help YAT-TSAU and his canine partner overcome obstacles in the hope of seeking YAT-CHOW's support in bridging the rift that's grown between her and her younger brother MA CHI-CHUNG (Oscar Leung).