London's teenage crisis

Gupta has long mined the rich seam of material that exists where cultures meet and clash. In last year's Sugar Mummies at the Royal Court she examined white female sex tourists in the Caribbean, while the acclaimed Gladiator Games dramatised the racist murder of Zahid Mubarek at Feltham young offenders' institution in 2000.

For White Boy she investigated the culture of bullying in inner-London schools and was stunned to discover how blasé some children were at the near-constant threat of violence.

"I find it shocking that kids are taking blades into schools. Girls have them in their bags. A lot of it is about bravado and having 'protection'. These kids don't necessarily know how to use a knife, but they have one because it makes them feel safe - obviously the opposite of what actually happens. You ask young people what goes on and they're very laid-back about it. As an adult, of course, you're petrified for them."

The hero of the play - the eponymous white boy, Ricky - is almost incidental to the killing itself. Ricky is Victor's best friend, a lad deeply unsure of his own roots, his cultural inheritance and his place in London's racial mix. He speaks, as many white kids in London do, not estuary English or even cod cockney, but with the street English of his black Caribbean heroes. He calls Victor "bredda" and Victor calls him "coz". It was this counter-cultural imitation that first caught Gupta's ear.

"You hear kids on street corners and you think they are black. Then you turn around and they're spotty white boys, whose friends are from all over the world. I find it lovely, because there's no distinction between black and white. But I also wanted to look at these boys who in a sense have lost their identity, because the way they speak is not actually who they are."

Gupta does not resolve Ricky's confusion; indeed, it is deepened by the murder of his best friend at the hands of a refugee, himself deeply scarred by his experience not only of war in Sudan, but of a hostile reception in Britain.

White Boy is very much a London play, and despite its violent denouement, in some respects it is also a celebration of London's multiracial youth.

"Forget all the dialogue and the acting," says Gupta, "if you just look at this play visually and see the friendship between Ricky and Victor, as they sit together on the stage and have a laugh - it's actually very powerful. You don't see enough of that in the theatre.

"We still tend to have Asian plays, or black plays, or white plays. That world of the Tube, where you sit and look around you and see all these amazing faces, isn't depicted enough."

She also maintains that, while racism still exists, inner-London schools are not inherently racist places. "You can't really be racist when you've got 23 languages in the same class."

Her own experience as a child growing up in the 1970s was very different. Her parents, a financial consultant and a civil servant, came from the Punjab in the 1960s and first settled in Hastings, East Sussex, where Gupta's most vivid memory of school is of shocking racism.

"I remember it clearly. I was eight, and I said to this one teacher, 'So-and-so called me a wog, sir.' And he said: 'That's because you are one.' Can you imagine? We moved to London a few years later, and that was great because suddenly we were among lots of other Asians." Gupta went on to win an assisted place to Mill Hill public school and then read modern history at Oxford.

She always wanted to write, but became a community worker in Islington before entering a BBC playwriting competition in 1991, which began a career on TV soaps. She once wrote EastEnders scripts and asserts - correctly - that to represent the modern-day East End accurately, the BBC should replace the Mitchells et al either with Bangladeshis or Eastern Europeans.

Gupta's first single drama for BBC2, Banglatown Banquet, was broadcast to acclaim last year, but her bread-and-butter writing these days is for Silver Street, the radio soap on the Asian Network, where she is allowed to tackle the issues that most interest her - Islamophobia, the radicalisation of young Muslim boys and the day-to-day problems encountered by ethnic minorities of all faiths and backgrounds.

Gupta never fights shy of controversy - she has written a screenplay for ITV about honour killings in the Asian community but claims, angrily, that the subject is too sensitive at the moment for a mainstream network. You can be sure White Boy will provoke strong reaction - and that is exactly what she's after.

"You don't want to come out of the theatre thinking, 'Oh, that was all right, I suppose.' If the audience comes out and they're weeping, or they're freaked or shocked, then I've done my job. That's what good theatre should always do - move you."

White Boy is at the Soho Theatre from 10 August (0870 429 6883).