Ma Yung Chen is a brash young boxer new to Shanghai. With his trusted pal Lo Keng Pei, he aims to improve his lot. He encounters the leaders of the local gangs. From the first, the elegant Mr Tan, he learns about money, and he respects Tan. But the second, the devious Tang, he despises. Tang employs a division of axe men (led by Chang, played by Guk Fung) and a division on knife men (leader played by Tien Cheng). Ma fights these divisions by himself, and does quite well.
A boxing contest is staged. The challenge is to knock down a gigantic European, and the prize is twenty dollars. With his irons fists, Ma naturally wins, and this also earns him boss status, meaning he now receives the proceeds of a protection racket.
But Ma wants more. He fights Chang for control of a street where casinos and brothels operate. Tang allows him to win, planning to use him as a pawn against his rival, Tan.