Ali G, portrayed by Sacha Baron Cohen, heads the fictional gang known as Da West Staines Massiv, a band of aspiring gangsters from the suburban town of Staines, situated to the west of London. Their main competitors are Da East Staines Massiv. The gang faces a significant blow when they discover that their cherished local leisure center—where Ali often relaxes and conducts his "Keep it Real" classes—is set to be torn down by the local council.
In a bid to protest this unjust decision, Ali and his crew decide to take action. When Ali goes on a hunger strike and is spotted chained to some railings, he catches the attention of the unscrupulous Chancellor of the Exchequer/Deputy Prime Minister, David Carlton (played by Charles Dance). This encounter pulls Ali into a murky world of political manipulation, as Carlton aims to use Ali as a pawn in a scheme to undermine the Prime Minister.
The situation escalates when Ali is unexpectedly put forward as a candidate for the upcoming MP election in Staines, which sparks chaos as he alienates nearly everyone he meets, including feminists and senior citizens. In a heated debate with his rival, he attempts to humiliate him by proclaiming that he “sucked off a horse.” Ironically, it is later revealed that his rival indeed has such a scandal in his past but attempts to justify it by claiming it was an accident during a hunting trip, which only adds to the absurdity of the situation. Consequently, Ali secures victory.
Initially appearing outmatched in his role as a Member of Parliament, Ali's eccentric tactics surprisingly begin to yield results. He embarks on a visit to a Customs checkpoint at Dover under the pretense of compiling a report, yet he ends up pilfering confiscated drugs and adult materials. His proposals, which include fostering "relatable" education and selectively allowing immigration of attractive women, surprisingly resonate with the public, leading to a surge in his popularity and a substantial increase in polling numbers.
In light of his unexpected success, the Prime Minister offers to rescue Ali's leisure center, but first, Ali is enlisted to join the Prime Minister at a United Nations peace conference aimed at diffusing potential conflict between Chad and Burkina Faso. As tensions mount, and with both the USA and Russia threatening nuclear conflict, Ali stealthily enters the catering area and dumps a bag of marijuana—which he had swiped earlier—into the delegates' tea, thus inadvertently forging a bond between the two opposing African presidents, who begin to express affection for each other.
As a result of his actions, the Prime Minister touts Ali as a hero who has saved the world. However, the truth of Ali's escapade comes to light when Carlton's secretary, Kate Hedges, uncovers evidence of Ali's mischief. She sends the incriminating empty bag to the press, leading to Ali's fall from grace in Parliament upon his return to the UK.
To make matters worse, an explicit video surfaces, showing Ali engaged in an intimate act with his girlfriend while wearing the Prime Minister's clothing, causing a public frenzy that forces the Prime Minister to resign. Consequently, Carlton, harboring animosity towards Ali, ascends to the role of Prime Minister and promptly orders the demolition of the leisure center. Moreover, he has strategically acquired real estate in Staines, anticipating the town's impending destruction for a new Heathrow terminal that would grant him immense wealth.
Declining an offer from Hedges to remain silent about the video in exchange for their own liaison, Ali and the West Staines Massiv embark on a frantic mission to secure the master copy of the CCTV footage that could absolve the former Prime Minister. They extend an olive branch to rival gangs throughout Staines and neighboring Berkshire, including the East Staines Massiv, to unite in their quest to acquire the tape from a vault.
Through teamwork and determination, they successfully retrieve the tape, allowing for the restoration of the former Prime Minister to his position, the saving of the leisure center, and a joyful resolution for all. Ultimately, Ali is appointed as the British ambassador to Jamaica, sparing Staines from the brink of destruction, while the reinstated Prime Minister decrees that Slough shall face demolition instead. This film also features a cameo from one of Baron Cohen's other famous characters, Borat, in a meeting with Ali G, showcasing the unique comedic styles that have become a hallmark of his work.
