Yard Gal Royal Court at the Ambassadors
Marie gives us the rundown. First of all, there's Threse. "She was in our posse. She was a white gal innit. Like me." She's big. And bold. "Ya didn't want to mess with that - you get me." Then there's Deanne. "She was sort of womanly. Big tits but then a real babyface innit." And Sabrina? "Her legs go right up to her bum din't they." And Deniz. "Her face was old - she look about thirty, but she was fifteen like the rest of us."

Not only is Yard Gal a portrait gallery, Marie (Amelia Lowdell) and Boo (Sharon Duncan-Brewster) play it to the gallery. Convulsed in nervous laughter, they size up the audience before egging each other on to begin. This new play by rising star Rebecca Prichard is the jive-talking story of a gang of girls scheming, dreaming and dealing on the streets of Hackney. Black, white and cruising for a bruising, they live the kind of lipsmackin', thirst-quenchin', ace-tastin' life undreamed of in Pepsi's philosophy.

A joint commission between the Royal Court and Clean Break - the company founded nearly twenty years ago to provide a voice for women ex-offenders and prisoners - much of its spirit derives from Prichard's year as the Creative Writing tutor in HMP Bullwood Hall in Essex. If that suggests the ambience of Birds of a Feather, think again. As she proved in her debut Essex Girls, there's far more genuine humour and compassion and far less sentimentality to her vision. Although the fast-cut language feels entirely authentic, swooping in and out of patois and slungback slang, the rhythmic punch and drive is both incredibly well-crafted and highly stylised. To describe it as poetry is not some sort of bogus lip service to trendy ideas about the supposed "rhythm of urban life", but a description of the meticulous construction of the dialogue. These "best friends from time" finish each other's sentences, bouncing details between them like a basketball. Then, just when you're ready to put the whole thing down as a high-energy, back-chat storytelling, Prichard sneaks up on you and catches you unawares. For example, Deanne's fall to her death from the balcony of a high-rise when high on drink and glue. Suddenly, the laugh-aloud one-liner dialogue fills out into long evocative speeches bringing out an unexpected pitch of emotion in the characters as well as the audience. Yet only later, when events spiral out of self-control, are the girls forced to take stock.

Director Gemma Bodinetz proves once again that she has a very sure hand when it comes to invigorating and illuminating dialogue. There are times when the stripped-down production threatens to overdose on its own energy and you occasionally wish she would let the text breathe more but the zest with which her two actors seize every detail is infectious.

Admirable though her intentions are, however, Prichard is out to prove a point and parts of the poignant yet defiant final section hover on the edge of didacticism. Nonetheless, her capturing of life - inside and out - is immensely skilful and affecting.

To 30 May, then touring (0171-565 5000).