Lin Guoquan (Simon Yam), the captain of the fleet of the Kowloon City Police Station in Hong Kong, is a conscientious and unremarkable uncle, but whenever he encounters an emergency in the streets, Brother Quan will show his skills and subdue the vicious villains. It turns out that Brother Quan was once an excellent police officer in the Criminal Investigation Department, but in order to take care of his mentally retarded son Xiaozhong who cannot take care of himself, he took the initiative to retreat behind the scenes and live an ordinary and monotonous life. When Brother Quan goes to work every day, he often leaves his son to the beautiful girl Lian Cuixin (Niu Mengmeng) to take care of him. However, due to frequent emergencies, the relationship between Cuixin and his girlfriend Zhou Jianghan (Li Canchen) is quite tense. Brother Quan and his buddies Luo Huawei (Lin Xue) and his apprentice Lu Qiaomei (Wang Ziyi) of the Criminal Investigation Team at that time were born and died in various dangerous situations. The passion in his body was ready to move, and he always felt the call of justice...