Plot

Four incompetent British terrorists set out to train for and commit an act of terror.

Four Lions tells the story of a group of British jihadists who push their abstract dreams of glory to the breaking point. As the wheels fly off, and their competing ideologies clash, what emerges is an emotionally engaging (and entirely plausible) farce. In a storm of razor-sharp verbal jousting and large-scale set pieces, Four Lions is a comic tour de force; it shows that-while terrorism is about ideology-it can also be about idiots.—Sundance Film Festival

In a British city, four men have a secret plan. Omar is disillusioned about the treatment of Muslims around the world and is determined to become a soldier. This is the most exciting idea Waj has ever heard. Better still it's a no brainer because Omar does his thinking for him. Opposed to Omar and everyone else on earth is the white Islamic convert Barry. He'd realize he joined the cell to channel his nihilism - If he had half the self knowledge of a duck. Faisal is the odd man out. He can make a bomb - but he can't blow himself up just now coz his sick dad has "started eating newspaper". Instead he's training crows to fly bombs through windows. This is what Omar has to deal with. They must strike a decisive blow on their own turf but can any of them strike a match without punching himself in the face?—Production

A group of Muslim Britons decide to launch a local jihad. Two of them go to Pakistan for training, with far less than ideal results. Meanwhile the others are cooking up half-baked plans. Turns out they're not that competent at being terrorists.—grantss

A group of radicalized young Muslim British men aspire to be suicide bombers. They are Omar (Riz Ahmed), the leading straight man who is deeply critical of Western society and imperialism; his dim-witted friend, Waj (Kayvan Novak); Barry (Nigel Lindsay), a bad-tempered and extremely rash White convert to Islam; and naive Faisal (Adeel Akhtar), who tries to train crows to be used as bombers.

Omar is married to Sofia (Preeya Kalidas) and has a son. Omar works as a security man at a local man. Barry teaches the group to swallow SIM cards to prevent the security agencies from tracking them, but Omar says that this is not helpful as the SIM cards can be tracked even after being swallowed. Omar decides to go to Pakistan for further training but refuses to take Barry along as he considers Barry to be a liability. Barry is livid at being insulted and insists that he will come, but Omar restrains him with jumper cables and leaves.

While Omar and Waj go to a terrorist training camp in Pakistan, Barry recruits a reluctant fifth member, Hassan (Arsher Ali). Barry was part of a religious panel debate panel on the moderate elements in Islam, and he finds Hassan in the audience who has radical views and believes that Muslims are being victimized in society. Omar has an uncle in Pakistan who connects him to the Jihadi trainers, who are located deep inside the mountain ranges. Waj stupidly carries a mobile phone to the training location and is admonished. The visit to the training camp ends in disaster, with Omar misfiring a rocket (Omar was trying to target a drone but held the missile launcher in the wrong direction when he fired it) that kills fellow jihadists and have to run away; however, he uses the experience to assert authority on his return to Britain. Omar and Waj claim that they were sent to special training to Somalia. Omar is livid to find that Barry recruited Hassan, who has a habit to make a recording everything.

Faisal buys a large quantity of bleach from the same shop and claims that he disguised himself by changing his voice. 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 "radicalize the moderates", but Omar considers this idiotic. Omar says that killing Muslims is no way to spread their message of rebelling against Western hypocrisy. Faisal wants a 9/11 type aerial bombing and decides to train crows to carry the explosives into buildings to implement his plan. Faisal simply ends up blowing a lot of crows during training. The gang tests their explosives in an empty field by blowing up household appliances by triggering the bombs remotely, using a mobile phone. Omar is worried that their group is being monitored.

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 neighbor Alice (Julia Davis) into their safe house; the group think they have been compromised and transport their volatile explosives to a new location in grocery bags. They drive in Barry's car, which breaks down hence forcing the gang to walk the rest of the way.

Faisal accidentally trips in a field, while carrying the explosives, and blows up. This causes a row among the remaining four, who disband after Omar says that he is calling the mission off. Later, they reconcile after Omar apologizes for his behavior, and Omar decides to target the upcoming London Marathon. Omar finds that the authorities have found Faisal's decapitated head in the field.

Wearing mascot costumes to conceal their explosives, Omar as the Honey Monster; Waj as a man riding an ostrich; Barry as a Teenage Mutant Ninja Turtle; and Hassan as an inverted clown they prepare to attack. Waj expresses doubts about the rectitude of the plot, but Omar convinces him to go ahead. Hassan loses his nerve and tries to alert nearby police officers, but Barry detonates his bomb using a mobile phone, killing Hassan and the police, as well as alerting the authorities to the remaining three.

Omar realizes he has led an unwitting Waj into something he does not want to do and sets off to make him change his mind. Police attempt to shoot Omar as he mingles with other runners but, instead, shoot a bystander dressed as a Wookiee. 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, causing a passer-by to carry out the Heimlich maneuver and detonate his bomb.

Waj is cornered by police and takes a kebab shop hostage. Omar then borrows a phone and attempts to talk Waj down. However, his call is interrupted by a police raid in which they shoot a hostage whom they mistake for Waj. Confused, Waj detonates his bomb, destroying the kebab shop. Distraught, Omar walks into a nearby pharmacy and detonates his own bomb.

It is revealed later that the police have arrested Omar's innocent and peaceful brother Ahmed as a terrorist; that they deflect responsibility for shooting the bystander; and that Omar and Waj killed Osama Bin Laden when Omar fired his rocket backwards in Pakistan.