East London, the late 1980s. Estate agent Clive 'Bex' Bissell is the leader of the ICC, a gang - or firm - of football hooligans. As he plays football with his firm, a rival gang, the Buccaneers, vandalise his car. While the rest of the ICC plan revenge on the Buccaneers, Bex goes home for lunch with his wife Sue and their young son Sammy. Trigger arrives at Bex's house and insists that they should strike quickly against the Buccaneers and their leader, Yeti. Bex disagrees.

At a bar in London, the ICC, the Buccaneers and another firm from Birmingham led by Oboe, meet to discuss joining forces for the upcoming European Championships. They argue about who should lead the united England firm in a campaign against foreign hooligans. Bex suggests they settle the argument with a fight. The ICC will meet Oboe's firm on Tuesday and the Buccaneers on Saturday. If the ICC wins both fights, Bex will lead them. They agree.

Bex visits his parent's house to collect the weapons he keeps in his childhood bedroom. He takes out a cosh and practices using it on his bed. Later, at his own house, Bex and the ICC plan their trip to Birmingham. The firm play a trick on new recruit Dominic, resulting in him having his arm slashed by Bex. They decide that four of them will travel to Birmingham in Simon's car; the rest will take the train.

On the way to Birmingham, Simon and his passengers stop at a service station. While inside, Yeti and the Buccaneers arrive and set fire to Simon's car. At the meeting point in Birmingham, Oboe's firm outnumbers the ICC. After a brief skirmish they flee. Yusef, the youngest member of Bex's firm, has his face slashed. While in hospital receiving treatment, he is questioned by the police. Later that night, Bex and Snowy go to Oboe's house, beat him up and slash his face.

At home the following morning, Sammy cuts his face with Bex's knife. Sue and Bex row over Sammy's injury and she asks him to give up fighting. Bex says he cannot, as he needs the buzz. Bex moves back to his parents' house. Later, Simon tells Bex that he will not be going on Saturday. Bex visits Yusef and commends him for his bravery. He says Yusef should not come on Saturday because of his injury. Bex argues with Yusef's brother Wesley about Yusef's involvement in hooliganism. Bex head-butts Wesley and leaves. Later in a pub, a strippergram arrives with a note for Bex. It's from Yeti and says Bex will be killed on Saturday.

At Bex's parents' house, the ICC pose for a 'team photo'. Dominic and Snowy tell Bex that they are too few to fight The Buccaneers and they don't want to go. Bex threatens Dominic and he and Snowy reluctantly change their minds. The police visit Bex's house with a search warrant. Sue tells them he has left her.

Saturday afternoon. At the match, the Buccaneers cannot find the ICC. Later, thinking Bex's firm were too scared to show up, they celebrate in a pub. Bex and the ICC arrive and a brawl ensues. Bex takes Yeti outside and beats him up. As Bex walks away, Yeti shoots him. On the eve of the World Cup, members of Bex's firm and Yeti's firm explain to a TV documentary crew that they have joined forces in Bex's memory.