A group of radicalised young British Muslim men aspire to be suicide bombers. They are Omar (Riz Ahmed), who is deeply critical of Western society and imperialism; his dim-witted cousin Waj (Kayvan Novak); Barry (Nigel Lindsay), a bad-tempered and extremely rash white convert to Islam; and the naive Faisal (Adeel Akhtar), who tries to train crows to be used as bombers. While Omar and Waj travel to an Al Qaeda-affiliated training camp in Pakistan, Barry recruits a reluctant fifth member, Hassan (Arsher Ali). The training trip ends in disaster when Omar attempts to shoot down an American drone and accidentally destroys part of the camp; the pair are forced to flee. However, Omar uses the experience to assert authority on his return to Britain.
The group begins acquiring materials for making improvised explosive devices but disagree about what to target. Barry wants to bomb a local mosque as a false flag operation to "radicalise the moderates", but Omar considers this idiotic. Faisal suggests blowing up a branch of the pharmacy chain Boots, but Omar states it is a not a worthwhile target. Hassan allows an oblivious neighbour (Julia Davis) into their safe house; the group suspect they have been compromised and transport their volatile explosives to a new location in grocery bags. Faisal trips up while crossing a field and is killed in the explosion. This causes a row among the remaining four, who disband. They later reconcile, and Omar decides to target the upcoming London Marathon.
Wearing mascot costumes to conceal their explosives, they drive to London and prepare to attack. Waj expresses doubts about the morality of their plot, but Omar convinces him and the group parts ways to detonate at separate locations. Hassan loses his nerve and tries to alert nearby police officers, but is killed when Barry detonates his bomb remotely. This causes the police to search for the remaining three.
Omar has a change of heart, feeling guilt about manipulating the easily led Waj into dying for a cause he doesn't understand, and attempts to prevent the attack. Police snipers receive Omar's description and shoot at him as he attempts to blend in with the runners, but mistakenly kill a bystander in a similar costume instead. Omar eventually contacts Waj from his mobile phone but is attacked by Barry, who swallows the phone's SIM card. However, Barry begins to choke on it, provoking a passer-by to carry out the Heimlich manoeuvre and in the process detonate his bomb, killing them both as Omar flees.
Waj is cornered by police in a kebab shop and takes the staff hostage. Omar borrows a phone and attempts to talk him down, but his call is interrupted when the police charge in and kill a hostage whom they mistake for Waj. Confused, Waj detonates his bomb, killing himself and the officers. Distraught, Omar walks into an empty pharmacy and blows himself up. In an epilogue, it is revealed that the police later arrested Omar's innocent brother as a terrorist; that they deflect responsibility for shooting the bystander; and that Omar unknowingly killed Osama Bin Laden when misfiring his rocket in Pakistan.Riz Ahmed as Omar, the only competent jihadi in his terrorist cell.
Kayvan Novak as Waj, the cousin of Omar; although stupid, he has enough sense to consult Omar or Barry before making decisions.
Nigel Lindsay as Barry, a rash convert with an explosive temper. Completely reckless and sadistic.
Adeel Akhtar as Faisal, a complete idiot who always trusts Barry. Has a father who may have dementia as he sees "creatures" that are not there.
Arsher Ali as Hassan, a rapper who joins the cell after Barry witnesses him pretending to blow himself up at a conference.
Craig Parkinson as Matt
Preeya Kalidas as Sofia
Julia Davis as Alice
Benedict Cumberbatch as Ed, a Special Branch Negotiator
Alex MacQueen as Malcolm Storge MP
Kevin Eldon as Sniper
Darren Boyd as Sniper
Mohammad Aqil as Mahmood
William El-Gardi as Khalid
Morris spent three years researching the project, speaking to terrorism experts, police, the secret service, and imams, as well as ordinary Muslims, and writing the script in 2007. In a separate interview, he asserts that the research predated the 7 July 2005 London bombings:
It was an attempt to figure it out, to ask, "What's going on with this?" This [the "War on Terror"] is something that's commanding so much of our lives, shaping so much of our culture, turning this massive political wheel. I was wondering what this new game was all about. But then 7/7 hit that with a fairly large impact, in that we were suddenly seeing all these guys with a Hovis accent. Suddenly you're not dealing with an amorphous Arab world so much as with British people who have been here quite a long time and who make curry and are a part of the landscape. So you've got a double excavation going on.
Morris suggested in a mass email, titled "Funding Mentalism", that fans could contribute between £25 and £100 each to the production costs of the film and would appear as extras in return. Funding was secured in October 2008 from Film 4 Productions and Warp Films, with Derrin Schlesinger & Mark Herbert producing. Filming began in Sheffield in May 2009.
Morris has described the film as a farce, which exposes the "Dad's Army side to terrorism". During the making of the film, the director sent the script to former Guantánamo Bay detainee Moazzam Begg. Begg has said that he found nothing in the script that would be offensive to British Muslims. The actor Riz Ahmed also contacted Begg, to ask whether the subject matter was "too raw". When the film was completed, Begg was given a special screening and said that he enjoyed it.
The film's music supervisor was Phil Canning. The song "Avril 14th" by electronic musician Aphex Twin plays during the film's ending credits.
The film premiered at the Sundance Film Festival in January 2010 and was short-listed for the festival's World Cinema Narrative prize. Introducing the film's premiere, Morris said: "I feel in a weird way that this is a good-hearted film. It's not a hate film, so I would hope that aspect would come through."
The UK première took place at the National Media Museum as part of Bradford International Film Festival on 25 March 2010, and was followed by a nationwide release on 7 May.
Despite its acclaim at the Sundance Film Festival, Four Lions failed to find a distributor in the U.S. for nine months, until the newly formed Drafthouse Films picked it up. The film had a limited release in the US on 5 November 2010.
Four Lions was released in the UK on DVD and Blu-ray on 30 August 2010, and in the U.S. on 8 March 2011.
Four Lions received positive reviews from critics. Rotten Tomatoes gives the film a "Certified Fresh" score of 82%, based on 126 reviews, with an average rating of 7.2/10. The site's consensus reads, "Its premise suggests brazenly tasteless humor, but Four Lions is actually a smart, pitch-black comedy that carries the unmistakable ring of truth." Metacritic gives the film a score of 68 out of 100, based on 28 critics, indicating "generally favorable reviews."
The Daily Telegraph wrote that "[Chris Morris's] evocations of the claustrophobic mundanity of the Muslims' lives, their querulous banter, their flimsily pick 'n' mix approach to the Koran all feel painfully, brilliantly real." The Daily Express rated Four Lions 4/5 and praised the performances in particular, calling the film "brilliantly cast with all the actors displaying sharp comic timing and both [Riz] Ahmed and [Kayvan] Novak also bringing out the touching humanity of their characters."
Upon its screening at Sundance, the Los Angeles Times and The Hollywood Reporter gave the film extremely positive reviews, the latter describing the film as "a brilliant takedown of the imbecility of fanaticism" drawing comparisons with This Is Spinal Tap and The Three Stooges.
Amongst the reviewers that gave the film negative and mixed reviews were Nigel Andrews of the Financial Times, who called the film a "spectacular miss" and The Guardian's Jeremy Kay, who wrote "as a satire on terror, Four Lions seems to be a missed opportunity". Andrew Pulver, also writing for The Guardian, gave the film a more favourable review, stating that "Chris Morris is still the most incendiary figure working in the British entertainment industry."
The UK premiere at the National Media Museum in Bradford was followed by a question and answer session with Chris Morris, Jesse Armstrong, Sam Bain, three of the principal actors, and two of the producers. Morris stated that he does not find the film at all controversial and that attempting to cause controversy is "one of the most boring things you can do". Morris also gave a talk introducing the film at a summer 2010 screening at Latitude Festival in Suffolk.
Despite an initial release on just 115 screens across the UK, the film was successful at the box office on its opening weekend, generating the highest site average of all the new releases (£5,292) and making a total of £609,000. According to the Official Top 10 UK Film Chart (7–9 May 2010), Four Lions was placed at sixth, behind Iron Man 2, Furry Vengeance, A Nightmare on Elm Street, Hot Tub Time Machine, and The Back-Up Plan. Due to its popularity, Optimum Releasing increased the number of screens showing the film to 200.
As of 8 August 2010, Four Lions grossed £2,932,366 at the UK box office. As of 13 March 2011, Four Lions the worldwide gross was US$4,353,954.
Time Magazine rated the film as among Top 10 movies of the year 2010.
The lead actors, Kayvan Novak and Nigel Lindsay, were both nominated for Best Comedy Performance in Film at the British Comedy Awards 2010. Kayvan Novak went on to win the award, thanking all his "brothers" — referring to his fellow actors in Four Lions.
At the BAFTAs 2011, Chris Morris won the award for Outstanding Debut by a British Writer, Director or Producer. He beat competition from The Arbor, Exit Through the Gift Shop, Monsters, and Skeletons.