Harry Brown is a 2009 British vigilante thriller film directed by Daniel Barber and starring Michael Caine in the lead role. The film is set in a run-down housing estate in London, where retired Royal Marine Harry Brown (Caine) lives alone, with his days passing by quietly until the violent murder of his best friend Leonard (David Bradley) by local gangsters.
At first, Harry tries to cope with the grief and move on, but as he witnesses the rampant drug dealing, prostitution, and gun violence on his doorstep, he realizes that the authorities are either unable or unwilling to protect the innocent residents. Enraged by the injustice, Harry decides to take matters into his own hands, and using his military training and ingenuity, he starts to hunt down the culprits one by one.
Harry's actions soon draw the attention of Detective Inspector Alice Frampton (Emily Mortimer), a sympathetic but by-the-book cop who tries to dissuade him from violence and arrest the perpetrators through legal means. Meanwhile, the gang's leader, Noel Winters (Ben Drew), aka "the Baron," becomes increasingly desperate to eliminate the "old man" who threatens his power and turns his own people against him.
As the tension rises, Harry faces not only the dangerous criminals but also his own demons and regrets from the past, including his role in the Northern Ireland conflict. In the end, Harry's quest for justice leads to a violent showdown that questions the morality and effectiveness of vigilantism, but also acknowledges the reality of a broken system that fails to protect its citizens.