Theatre Mules Royal Court Upstairs, London

In a luxury hotel room, three sleek young black women are panicking. They are high-class "mules" (or drugs couriers) and one of their colleagues has absconded with the dope. If they don't effect a delivery in Amsterdam that day then they're done for. "I can't lose this job. I can't do anything else. Can you see me working in Woolworths?" asks the terrified Sammie, who has risen above her humble origins by carrying drugs for a living, and now spends her earnings on works of art.

Winsome Pinnock's pacy and fascinating play opens with all the punch and pizzazz of a Hollywood action movie, but hijacks those conventions to expose a sorry tale of exploitation. We watch the glamorous Bridie (Clare Perkins) in action, recruiting young, vulnerable and desperate women and turning them, as she says with pride, into affluent professionals. Her first stop is Jamaica, where the sisters Lyla (Sheila Whitfield) and Lou (Abi Eniola) are unsuccessfully trying to get out of the ghetto by "higgling" (selling) second-hand knickers and bras on the street. Back in London, Bridie appears like an angel of mercy when Liverpudlian runaway Allie has hit rock bottom. But even Bridie is merely a minion for the all-powerful unseen Cliveden, whose operation it is.

The play is rich with the multifarious accents, intonations, speech patterns and dialects of the various communities represented. "Don't bother a turn you nose up after we underwear because we ain't got nuttin' big enough fe batty like yours!" shouts Whitfield, the not so successful saleswoman, and Pinnock also catches the idiosyncratic voices of an imperious Nigerian exile called Olu, Liverpudlian Allie, cockney Rog and American Bridie.

The three actors in Roxana Silbert's production are versatile enough to meet the demands placed on them, but it is a shame that the richness of the writing had to be met with penny-pinching in production. Financial constraints and the fact that the play will tour small-scale venues meant that only three actors were hired for 12 very different characters. There's no doubt the production suffers, as scene changes that should be swift and effortless are marred by actors having to fumble with one irksome costume after another.These are problems which direction and design ought to solve.

Pinnock's great achievement, however, is that, having been commissioned by the Royal Court and Clean Break Theatre Company to write an issue-based play, she has come up with something that is neither pious nor proselytising. Mules is non-judgemental, obliquely pointing up how spiritually barren is the materialistic life that seems to be the only alternative to an equally brutalising poverty trap. That's not to say that the audience aren't indulged with a little of the vicarious pleasures of big spending along the way.

n To 18 May. Booking: 0171-730 1745