After releasing his three-part musical drama sensation Shiro's Story via YouTube (20 million views and counting), British rapper-turned-director Andrew Onwubolu, aka Rapman, makes his feature debut with a searing look at inner-city gang violence. While Blue Story doesn't quite reach the heights of US genre landmarks Boyz n the Hood and Menace II Society, Rapman has clearly watched both on repeat. Far more hard-hitting than British-made equivalent Kidulthood (and its follow-ups Adulthood and Brotherhood), this tale of a postcode war packs a huge punch.

What might seem ripped straight from a knife-crime headline in London's Evening Standard is actually inspired by events from Rapman's own upbringing. The narrative focuses on the Deptford-raised Timmy (Stephen Odubola), who befriends the Peckham-based Marco (Micheal Ward). As events unfold, these two find themselves on separate sides of an increasingly ugly gang rivalry – a street battle where there really are no winners.

One of the selling points here is that Rapman occasionally pops up in the background, narrating the action with his rhymes. It's a technique that Plan B deployed in his 2012 film Ill Manors, though he was never actually seen on screen. While it gives Blue Story its own flavour, Rapman largely departs from the conceit in the second half, when the action ramps up, gets more intense and the film heads towards a vicious conclusion.

Although the use of street slang will confuse some, there's no disputing the integrity of a tale that will leave you shaken and stirred by the climax. Rapman draws compelling turns from Top Boy star Ward and newcomer Odubola. Their performances add poignancy as we watch a friendship struggle to survive a world in which threats of stabbings and shootings are normal.

General release from Fri 22 Nov.