In the late 1950s and early 1960s, Hong Kong was full of collusion between police and criminals. Among them, the Kowloon Walled City was a chaotic place where dragons and snakes were entrenched and people were frightened. The idle young men Ah Hao (played by Liu Qingyun) and Ah Le (played by Wu Zhenyu) accidentally mixed here, and were infected by the chaotic atmosphere here, and they were reluctant to leave. They partnered to gamble on horses and defraud money, which attracted the pursuit of the banker. Fortunately, the big brother of the walled city, Fei Bao, saved their lives, and the fate of the two changed from then on. Ah Hao worshipped Fei Bao, and later fell in love with Fei Bao's sister-in-law Dadan Ying (played by Pang Dan). He was courageous and brave, and he was in the limelight; Ah Le became a policeman and married Fei Fei (played by Zhu Yin), a girl who had an affair with Ah Hao. In order to let his vain wife live a happy life, he did not hesitate to choose corruption and depravity. Two good brothers in the black and white ways, work together to fight for a world of their own...