Harry Brown is a British vigilante crime thriller film directed by Daniel Barber and starring Michael Caine, Emily Mortimer, Jack O'Connell, and Liam Cunningham.

The film also features actor and artist Ben Drew (Plan B) who, with Chase & Status, is also responsible for the film's theme music track "End Credits."Harry Brown had its World Premiere as a "Special Presentation" at the 2009 Toronto International Film Festival and was released theatrically in the United Kingdom on 11 November 2009; the film will receive a North American release on 30 April 2010.

The story follows Harry Brown, a widowed Northern Ireland veteran living on an Elephant and Castle housing estate that is rapidly descending into youth crime. Harry takes up violent methods to curb crime after a friend is murdered.

Plot
The film opens with a gang initiation, where a boy living on a council estate in South London is made to take drugs and hold a pistol. After this, in a scene apparently filmed on a mobile phone, three gang members joyriding around the estate on a motorcycle harass and shoot dead a mother walking her child. While fleeing the murder scene, they speed across a road in front of an oncoming truck and are also killed. The titular Harry Brown (Caine), an elderly former Royal Marine and Northern Ireland veteran who is suffering from emphysema, wakes to news of these deaths over the radio. In order to visit his hospitalised wife Harry must cut through a public underpass, which is a gathering spot at all hours by local thugs and gang members.

Though seeing the increasingly brutal facts of life on the estate (including a man beaten for attempting to intervene when his car is broken into by a gang of youths) Harry is unwilling to get involved. His only real friend is Leonard (Bradley), another pensioner who complains that hooligans put dog faeces through his letterbox and spit on him. The pair spend their days playing chess at a pub run by Sid (Cunningham), who takes kickbacks from a pair of drug and arms dealers. Leonard cannot forgive this, but Harry is willing to ignore it in order to keep out of trouble. The night Harry finds out about the bribes paid to Sid by the gangsters, Harry is informed his wife is dying. In order to reach the hospital before she passes away he must go through the underpass, but he is too scared to do so, and by the time he finds an alternative route to the hospital his wife is already dead. After the funeral, Leonard confides that he can no longer take the insults and indignities the youths foist upon him and he shows Harry a First World War bayonet he now carries. When Harry tells him he should put the knife away and talk to the police Leonard admits he has done so but they ignored him. That night Leonard wakes in his flat to find someone has put burning dog faeces through his letterbox.

The next day Harry is visited by DI Frampton (Mortimer) and DS Hicock (Creed-Miles) who tell him Leonard was murdered in the underpass. Members of a local youth gang, including Noel Winters (Drew), are arrested but refuse to answer questions and are released. Although sympathetic, Frampton admits to Harry that because Leonard was murdered with his own bayonet the crime will be manslaughter or self-defence, which appalls Harry even more. In the aftermath of Leonard's funeral (which only Harry attends in full), Harry gets drunk at Sid's pub. Walking home he is attacked by one of Winters' recently released gang members (Oakes) who attempts to rob him with a knife. In a drunken daze, Harry's muscle memory from his Royal Marines training allows him to turn the knife on the robber, killing him. Rushing home and washing the blood off himself, Harry decides the need for vengeance or self-defence.

Harry follows one of the drug-dealers, Kenny (Gilgun), from Sid's pub to a squalid den and manages to talk himself inside on the pretext of purchasing a pistol to "shoot pigeons on his roof." The drugged-up dealers are growing copious amounts of cannabis and making pornography, and when Harry arrives he finds one of the girls abused in these videos is sprawled on the sofa and suffering from a drug overdose. The scarred and sinister dominant of the two dealers, Stretch (Harris), explains that he keeps her in a drugged state in order to use her as a prostitute. Harry recommends the dealers phone for an ambulance to help the girl, and after being threatened with a pistol ends up killing both dealers, setting fire to the cannabis and driving the comatose girl to a local hospital. The police are confused at the seemingly random killings of the dealers coupled with the "rescue" of the girl. Harry, meanwhile, has a bag full of fire-power.

Surveillance of the youth gang (including more thefts and assault) leads Harry to kill a major drug-trafficker and kidnap Marky (O'Connell), a newly inducted member of the gang (who, we were told earlier, has been sexually abused throughout his life and is seen here giving oral sex to the trafficker). Harry tortures the boy and threatens to kill him, and Marky admits footage of Leonard's murder was recorded on his phone. After watching the footage, and knowing who among the gang committed the murder, Harry takes the boy (bound in sellotape and on a dog's leash) down to the underpass, where Winters and another gang member are making out with underage girls. After a tense scene in the darkness, the ensuing gun battle sees Winters escape, Marky and another gang member killed, and Harry suffering an emphysema attack, leaving him to be taken to hospital.

Certain that the murders of drug-dealers are related to a gang-war, Police Superintendent Childs (Glen) orders an operation to arrest major players in the estate's criminal fraternity. DI Frampton remains unconvinced, however, and informs him that her investigation has led her to believe Harry (who has links to all the dead) is the killer. The Superintendent has her removed from the case and transferred to another department. The late-night, no-knock raids on various gang members of the estate results in a riot, with teenagers coming to "join the fun" in attacking the police. As the estate burns, Harry discharges himself from hospital and heads off to get his final vengeance on the vindictive Winters. DI Frampton, fearful for both Harry and Winters safety, takes a cynical DS Hicock into the rioting estate to find the pair before more blood is spilled. In the process the two police detectives are attacked by yobs and Hicock is badly injured. Harry rescues them and takes them to Sid's pub, where he tells Sid to phone for an ambulance.

While Sid is out of the room Frampton drops a bombshell on Harry by telling him Sid is Winters' uncle and therefore Sid has been part of the gang all along. Searching the pub, Harry finds both Winters and Sid, and shows Sid the phone footage of what his nephew did to Leonard. Sid seems horrified by it, but tells Harry he cannot allow his blood relative to be killed in vengeance. Harry, torn between his friendship and still suffering from emphysema, is tricked into turning his pistol over to Sid, who proceeds to beat Harry up.

In the climax, Frampton tries to phone for armed backup but is stopped by Winters. Taking control of the situation, Sid tells Winters the only solution is to kill Harry, Hicock and Frampton, and then dump their bodies outside. Sid suffocates the injured Hicock to death with his bare hands, while Winters begins strangling Frampton. Suddenly Harry draws a hidden revolver and shoots Winters dead. Just as the anguished Sid goes to shoot Harry a pair of laser sight appear on his chest - showing Frampton's call to her superiors did get through. Before Sid can fire he is gunned down by CO19 armed response officers.

At a conference held after the riot, SI Childs explains that DS Hicock will receive a posthumous commendation and that the police raids have lowered crime on the estate, going on to refute claims that a "vigilante" had anything to do with it. The final scene is of Harry Brown walking toward the underpass, which is now quiet and safe.