The government imposes the ban on chocolate ! Well, that might be a stupid point to start a movie, but it handles the idea very well: if you forbide something that people want, they will fight to get it back. Black market will appear, and everybody that we know will suffer the consequences.
It is a good family movie, but also it works at another level: replace the word "chocolate" by "cocaine", "pot", "heroine", or "iron maiden LPs", and you'll get the idea. The writers have managed to understand the mechanics of the black market and all the clichés of the underground movements and put it into a nice Sunday evening cable movie. Of course that it went unnoticed under all the Harry Potter hype, but it has that kind of stories that will touch some kind of fiber in you, even with all those clichés flying around.