However, I have to give you some facts about the film for a better understanding:
1. main theme:
The main theme of the film is the violence from among the ranks of the UK football fans in the Premier League and the impact of the foundation on Matt Buckner.
The foundation in the movie is the "Green Street Elite". The short form of it is "GSE". They are a kind of fan club, but in their believe they are a firm. The GSE supports the football club West Ham United.
Every team of the Premier League has his own firm. A big problem is, that every firm wants to be the strongest and most dangerous one. That's why there are much fights and often seriously injured person after that.