The early scenes of this London-based thriller promise much. Toby Kebbell has a fine impassive stare as the title veteran, a paratrooper who's come home from the Middle East isolated and quietly enraged in a sink-estate that's almost a war zone in itself.
Through an army pal he becomes involved in an undercover op tracking rogue jihadist cells, though it's the personal safety of the go-between (Adi Bielski) that most concerns him. Brian Cox and Tony Curran bring heft to the shadowy security bigwigs running the show. Sadly, Matthew Hope's film loses it badly in the last 15 minutes as the veteran's (and the film's) purposeful calm descends into a Taxi Driver-style bloodbath.