The story and screenplay were developed by former hooligan turned author Dougie Brimson. Throughout the film, the Green Street Elite fight other "firms" such as Tottenham Hotspur's Yid Army, Birmingham City's Zulus, Manchester United's Red Army and Millwall's Bushwackers. A sequel called Green Street 2: Stand Your Ground, was released straight-to-video in 2009.
Plot
Matt Buckner (Elijah Wood), a journalism major, is expelled from Harvard University after cocaine is discovered in his room. However, the cocaine belongs to Jeremy Van Holden (Terence Jay), his roommate. Buckner is afraid to speak up because the Van Holdens are a powerful family, and Jeremy pays him $10,000 for taking the fall. Matt visits to the United Kingdom to stay with his sister Shannon (Claire Forlani), her husband Steve Dunham (Marc Warren) and their young son, Ben (James Allison). There, Matt meets Steve's brother, Pete (Charlie Hunnam), a loud and thuggish Cockney who runs a local football hooligan firm - a group of football supporters that arranges fights after matches - and teaches at a local school. Steve asks Pete to take Matt to a football match between West Ham United and Birmingham City, though Pete is reluctant to take a "Yank" to a football match, because of the xenophobic nature of his friends. He is persuaded because Steve will only give the money Pete needs to Matt. After defeating Matt in a fight, Pete decides to take Matt to the football match, thinking he might learn a thing or two.
Matt meets Pete's friends and his firm in the Abbey, their local pub. The hooligans all befriend Matt, with the exception of Pete's rather obnoxious right-hand man, Bovver (Leo Gregory). After a few pints of lager, they head to Upton Park for the match. After the match, Pete, Bovver, and the other firm members agree to go and fight some Birmingham fans, but Matt decides that it is not for him and tells Pete he is going to take the train home. On his way back to the underground, Matt is jumped by three Birmingham fans, who nearly give him a 'Chelsea Grin', but he is rescued by some GSE members, who are on their way to a larger fight. Though grossly outnumbered, the GSE manage to hold their ground until reinforcements chase off the Birmingham firm. Matt does well in his first true fight and is inducted into the GSE. After a row with Steve, Matt moves in with Pete, and the two exchange stories.
The GSE firm then head to an away game against Manchester United. Matt was not meant to come but ends up sneaking onto the train. Whilst on the train they are pre-warned that 40 Manchester United firm members are waiting for them at the station. Bovver hits the emergency stop button which allows the GSE to get off at an earlier stop (Macclesfield). Having failed to find a taxi, they persuade a van driver to take them into Manchester. Matt sits in the front of the van with the driver; the rest of the GSE are in the rear. As the van approaches the Man Utd. fans, Matt tells them that they are moving equipment for a Hugh Grant film, so the fans let them through. When past them, he stops the van, opens up the back, and the GSE charge out to attack the United firm members. They win the fight and run away singing "There's your famous GSE!"
It is soon revealed to Matt that the GSE's sworn enemy is Millwall's firm, led by Tommy Hatcher (Geoff Bell), with whom Bovver makes negotiations after getting jealous of Matt. After one of the members of the firm see Matt meeting his father, a renowned journalist for The Times, for lunch, they assume Matt is a "journo" as well. Bovver informs Pete of this, and, when Steve finds out, he goes to the Abbey to warn Matt. Matt finds out that Steve used to be "The Major" of the GSE but quit following a match against Millwall, to which Tommy Hatcher brought along his 12-year-old son. The boy was killed in the ensuing fight by members of the GSE, causing Tommy Hatcher to "lose it," blaming Steve and the GSE for his son's death. After witnessing this tragedy, Steve left football hooliganism for good.
At that moment, Bovver and Pete arrive, and there is a massive argument in the Abbey, in which Bovver comes out humiliated. Infuriated, Bovver goes to Millwall's local and asks Tommy Hatcher to ambush GSE at the Abbey. Initially reluctant, Tommy Hatcher agrees upon learning that Steve Dunham is there. Pete angerly confronts Matt in the bathroom over the covering-up of his real identity. The Millwall firm then crash the Abbey, and petrol bomb the bar. Upon arriving, Tommy Hatcher confronts Steve. Steve's attempt to convince Tommy Hatcher that he is no longer involved in the GSE only further reminds Hatcher of his son, and he stabs Steve in the neck with a broken bottle, telling him that if he dies tonight then they are both even. Bovver, who had been knocked out by Tommy Hatcher, comes round just in time to help Steve, who is badly injured. At the hospital, Pete blasts Bovver for his betrayal. Shannon decides to head back to the United States to ensure the safety of her family.
In the aftermath, the two firms meet near the Millennium Dome for a bloody and all-out brawl. Matt and Bovver show up to fight for the GSE, but during the fight, Matt's sister, Shannon, turns up with their son, and are attacked by a Millwall hooligan. Matt and Bovver come to their rescue. Pete notices that Tommy Hatcher is approaching the car, and distracts Tommy by taunting him to "finish him off." When Tommy Hatcher declares to have finished with him, Pete then retorts that Tommy Hatcher was to blame for his son's death, having failed to protect him, shouting "he was your son!". Tommy Hatcher, driven to insanity, attacks and beats Pete to death, all the while shouting out a variation of the words to the chant 'Only a poor little Hammer,' using it as an analogy for Pete's condition. The fight completely halts at this point, and Hatcher is eventually pulled off Pete by some of his friends as he breaks down in tears. Everyone on both sides gathers around Pete's dead body in shock, with Bovver sobbing at his side.
Matt returns to the United States and confronts Jeremy Van Holden in a restaurant toilet, where Jeremy is snorting cocaine. Jeremy arrogantly tells Matt to leave during a brief discussion in which he admits to his identity as the cocaine stash's true owner. Matt then pulls out a tape recorder and plays back what Jeremy just said, saying that it is his "ticket back to Harvard." Jeremy lunges at him to try to get the tape, but Matt casually reverses the attack and raises his fist as if to punch Jeremy. He does not do so, instead walking out with a smile as Jeremy collapses to the floor, defeated. The film ends with Matt walking down the street outside the restaurant singing "I'm Forever Blowing Bubbles."
