A Cabinet minister is gunned down outside his home in London by a member of the Provisional IRA. Security protocols come into immediate effect, but the assassin evades them and manages to get back to Belfast unscathed. The military send Captain Harry Brown - a soldier who specialises in deep cover work in hostile situations - into the Falls Road area of Belfast, a place notorious for civil unrest. His mission: to infiltrate himself into the local population, hunt down the assassin and kill him on his own territory - proving to the IRA that they are not safe, even in their "own back yard". It is a terrifying game of cat and mouse, taking place in a civilian-occupied war zone, where one mistake means certain death.