The city is being overrun by gangs, and the notorious Axe Gang is the worst of the bunch. The only folks who'd been safe were the residents of the slums, who were too poor to be bothered with. But now, the residents of Pig Sty Alley find themselves on the Axe Gang's bad side, and a series of epic battles is the result.
This is a very weird movie, a mix of stupendous martial arts sequences and extremely broad slapstick. At moments, the comedy turns the movie into a live-action cartoon; there's a chase scene where the characters' legs spin as they run, like something from a Road Runner film.
The fight sequences are spectactular. I was particularly impressed by a scene involving two villains who play a traditional Chinese harp; each strum of their fingers across the strings lets fly a ghostly knife or sword or warrior, and the battle provides its own soundtrack music.
There are a lot of in-jokes and references to other movies along the way. I caught references to The Matrix, The Untouchables, Spiderman, and The Shining. I'm sure there are also a lot of specific references to other Chinese/Hong Kong action movies, and I think that some of the fight scenes are meant to be parodies of certain conventional martial arts styles.
But for me, the action and the comedy didn't mix very well. And though I've enjoyed other movies in which the martial arts sequences bend the laws of physics, this movie shatters them completely, which I found far less interesting and effective.