The opening scenes feature several people being killed in a dark room while other, so far nameless men, sit and make important looking gestures. This is followed by an execution, followed by one of the executioners (We'll call him "The Hero" finding his family slain, which sets up the expected vow of revenge theme common to the genre. Finding his Nephew alive and stuck in a nearby well he uses the child to set a trap for the killers, whom he trounces with ease. He then sets off to find whoever paid them, after resigning his "post" no idea what his post was. Leaving the child with "Uncle Ko" he stomps off to the home of his family's killers, where he continues to beat the snot out of anyone in his way. Finding that this is just a middle-man in the plot against him, he gets the name of the next guy he has to track down. By this point his nephew has escaped and tracks him down to join him in his quest.
This is a slightly confusing movie due to some moderately bad dubbing (some of which provides (un? intentional laughs) and also due to several dark scenes where everyone seems to be wearing black on a black street on a moonless night, and I don't know much about actors etc in fu flicks so I thought I'd just give a general breakdown of the movie's plot.