This story revolves around Ho Hofai, the legend of the Hong Kong police force, who is known as the reputable "Three Tigers of O" alongside his mentor Fok Kaichyun and his junior Chan Yiuyeung. After Ho Hofai falls into the trap of the gangster Jau Hung while trying to save his mentor in an operation, he falls from grace overnight. After joining the Emergency Unit, Ho Hofai, young police officer Siu Tzutsun, veteran driver Ziu Siutong, and other colleagues charge at the forefront and gain insight into the mastermind behind Jau Hung's case. The Hong Kong government establishes a special operations team, which Ho Hofai and Siu Tzutsun join. After multiple hardships, they finally crack the case and thwart the evil "one country, two systems" plot of foreign forces attempting to target Hong Kong's financial system. Ultimately, Ho Hofai avenges his master, redresses his grievances, and safeguards Hong Kong's prosperity and stability.