Mike Greene, along with other members of the GSE, are arrested for participating in the fight at the end of the first film, and end up being sent to a tough prison. In prison, the GSE quickly discover the brutality of life on the inside, as they are constant targets of the superior numbered and better-financed Chelsea crew. After a quick brawl the GSE get blamed for the assault and are transported to another prison where a huge number of Bushwackers are waiting for them. Soon after arrival the crew meet up with Marc and his crew, who declare their intentions to make the GSE's time in the prison tough. After throwing an insult about their deceased leader, Pete, they fight, are restrained and are, once again, blamed for the incident.

Soon after, Mike meets up with some Spurs supporters, who offer him advice about surviving in prison. They soon find out that this isn't easy, because the Bushwackers are aided by a prison officer, Veronica, who also provides them access to cigarettes and drugs. She also gives them a key to go where they want, which they use to attack a GSE member in Segregation, who is only narrowly rescued by an officer, Officer Mason, who also aids the GSE.

The GSE realize that in order to survive, they need to stand their ground and, with the assistance of Mike, they corner and assault two of the Millwall fans. Soon after this Marc threatens Mike. Mike uses Marc's tactic against him and by beating up the Millwall fans and pretending to be the victims. Angered, Marc gains access to segregation where Mike is sleeping after being sent there and assaults him. However, after one too many Pete taunts, Mike gains the upper hand and is seen to be winning the brawl until Veronica and several police officers breaks it up.

Due to lack of space, the prison Governor asks Veronica and Officer Mason to select 63 people to set free, under the circumstances that they will not damage society if let go. Veronica intentionally chooses most of the Millwall fans, even though they are mostly troublesome, but the Governor spots this. Officer Mason provides a more suitable list of which he agrees to, apart from the three members of the GSE who have been trouble since they came. Veronica then asks for three of her Millwall fans to be set free instead, but the Governor has an idea to let them compete for this prize by arranging a football match.

Marc notices Mike's girlfriend at several visiting days and orders two of his friends on the outside to keep her hostage. Marc threatens Mike that he will kill his girlfriend unless he throws the match. Before the match begins, Mike informs his friend, Ivan of what is going to happen and tells him to call his friend to go over to the house and save his girlfriend.

As the match begins, a gruesome fight breaks out while play is going on and Mike deliberately plays badly so Millwall can win. However, the GSE arrive Mike's house to save his girlfriend. Ivan then gives Mike the signal that she is okay, and Mike stops throwing the game. Millwall stand no chance with West Ham outplaying them completely and Mike scoring the winning goal. After the game ends, Marc, now distressed at Mike, goes up to him, but he and his two friends are detained for kidnapping Mike's girlfriend and Veronica is also arrested on a charge of drugs trafficking. Officer Mason is promoted and Mike and his friends are set free.

The film ends with the 3 boys out of prison and, though Mike wants to spend time with his girlfriend, the GSE have organized a party for them to celebrate, which they accept.