It starts in a casino. The big winner gets robbed after leaving. Back at the gambling table a guy uses his blood to bet. As expected, a fight breaks out. It is a typical brawl as Tien Peng strikes left and right as dozens of stunt men hop around behind him. It stops when the casino boss (Huang Chung-Hsin) arrives and offers him a box of coins. Some sort of deal is arranged. He agrees because mother is sick in bed.
Cut to some guy tries to kill himself and another guy stops him. They go to eat and talk. Cut again to the casino boss confronts a woman (Lisa Chiao Chiao) at her house. There is a fight and she seems to agree with his demands and later seems romantically involved with him. Back to the two guys and one goes to the casino. Another fight results.
At about the thirty minute mark Tien Peng and Chiang Pin get into a fight and they discover Tien has a hard head and Chiang has a hard arm. The title refers to these two guys!
My copy is a digital file made from the German VHS release. There are no subtitles just German dubbing and I do not speak German. To my knowledge this was released on VHS only in German and Italian. I am on a mission to watch every movie made in the golden age of martial arts movies from 1967 to 1984. I have watched many without English and usually it is not that hard to figure out the story. However, in this movie I could not follow any story line at all other than the reason for the title.
The fights are typical of the early 1970s but different for two reasons. They are almost all hand to hand and there is no wire work or even trampolines. That could be a good thing but unfortunately the fights all look alike. I can only rate this as low average and doubt I will watch it again.