CID officer Lai Yat-tsau (Bosco Wong) parents died early, leaving him to take care of his three younger sisters. First younger sister Lai Suk-chu (Kayi Cheung) is a prestigious kindergarten school superintendent who is kind but gullible. Middle younger sister Jil Lai Suk-si (Tracy Chu) is a luxury brand salesperson. She is immature and money hungry. She originally dated Yat-tsau's partner Fai Chung-lim (Raymond Wong) because he is a rich restaurant heir, but after years of dating she really fell-in-love with him and wants him to quit the police force because of the dangers that comes with the job, also for him to return to being a rich heir. Youngest sister Fanny Lai Suk-fan (Angel Chiang) is rude and lazy, who refuses to find a job. She is also the only one in the family that is married. Her husband Ma Chi-chung (Oscar Leung) works at the Agriculture, Fisheries and Conservation Department, but his attitude is very similar to his wife and often mooches off of his in-laws. Lai Yat-tsau is a reckless cop who does major damages to the streets of Hong Kong when he is chasing crooks. His recklessness drags his partner Chung-lim down with him. Together the pair are nicknamed "Faw Sui" Sir (which means "Kerosene" in Chinese) and "Fai Chia" Sir (which means "Firewood" in Chinese) because the two are tend to start a fire. When Yat-tsau's former informant Lui Kam-bo (Jerry Ku) seeks his protection from his recently released older twin brother Lui Kam-dong (Jerry Ku), that Kam-bo had helped Yat-tsau put in prison. Yat-tsau trails Kam-dong's every move to make sure he doesn't kill Kam-bo. During a drug bust between Kam-dong and his former gang, Yat-tsau gets attacked by the gangs guard dog named Bah-da (Hong Kong saying of the English word "Brother"). While recovering from a dog bite in the hospital his meets Ma Chi-ho (Linda Chung), who is more concern for Bah-da then Yat-tsau's injuries. Chi-ho's political correctness and bluntness ends up offending Yat-tsau which leads to thWatch drama online for free.