Mogadishu, by first-time playwright Vivienne Franzmann, won the 2008 Bruntwood Prize under the aegis of the Royal Exchange, Manchester, and Matthew Dunster’s powerful production comes straight from that address to the Lyric.

In some ways, this is becoming dangerously over-familiar territory: mouthy, dead-end London school kids, dysfunctional single parent families, fraught teachers, violence and apathy, gutter language, blatant sexuality, a sense of total breakdown and topsy-turvy social agendas.

But Franzmann, who taught for 12 years in just such a London school, pushes the boundaries by writing some really superb, ambitiously extended scenes between the characters who satellite troublemaker Jason (Malachi Kirby), a black 15-year-old who pushes over a white female English teacher, Amanda (the always excellent, emotionally direct Julia Ford) in a playground rumble and turns the incident inside out in order to save his skin.

There’s one crucial fact about Jason’s life that is conveniently withheld for too long, but otherwise the stage crackles with confrontation, accusation, self-justification and threat. The setting by Tom Scutt is a circular cage-like fencing that is cut and frayed with years of neglect and decay, cleverly lit by Philip Gladwell to cover the smooth scene changes and scenic overlaps.

Jason’s dad, a security officer (Fraser James) stands by him but wants a change of attitude. For Amanda, the affair spirals into a nightmare of ebbing support at both home - where she’s domiciled with a second husband (Christian Dixon) who happens to be black, adding another layer of difficulty in the cultural shake-out - and in the staff room, where Ian Bartholomew is a cowardly, box-ticking headmaster anxious “to be seen to be accountable” in the aftermath of the fracas.

The social services, too, want to know if she can care properly for her own daughter. That daughter, Becky, is frighteningly well played by Shannon Tarbet, an outstanding newcomer in Spur of the Moment last year at the Royal Court.

Jason’s mates are played by a group of outstanding young actors similar to those in the Bush Theatre’s educational season earlier this year. Where do they find them?

The title? Self-harming Becky taunts Amanda with the aspirations she’s supposed to have: university and a gap year building irrigation systems in Mogadishu and knowing who Judi Dench is. It’s not even a dream, it’s an illusion.

And Malachi Kirby’s broody, bullying Jason is a perfect expression of adolescent insecurity whose impact is so disastrous on other people and not least himself. It’s a sad, sad play, but a very good one, and much more than just promising.