A large number of new immigrants have poured into Hong Kong. Many of them are aggressive immigrants, and many of them are in the same league with the local underworld. But after all, they are regarded as outsiders and called "big circle". Cheng Zhihu and Cheng Zhipeng, two brothers who are new immigrants from the mainland, came to Hong Kong to earn a living with their sister Cheng Shaoming and brother-in-law Zhiwei in the mid-1970s; Hu is famous in the underworld because of his bravery and skill, but "Big Circle" can't escape the bad luck of being used after all. In an action, Hu was jailed for his boss, and he decided to break away from the underworld after he was released from prison; But Peng followed his brother's footsteps in just a few years.