Blue, Latchmere Theatre, London

Ursula Rani Sarma is a 24-year-old playwright from County Cork who is already under commission from the National Theatre in London, Edinburgh's Traverse and the Abbey Theatre in Dublin. Cardiff, it seems, has been pitiably slow off the mark here. What, one wonders, is holding the Welsh back?

The beguiling freshness in Rani Sarma's writing that must have attracted these institutions is abundantly in evidence in her play Blue. This beautifully acted production by Joss Bennathan has the measure of its tricky tonal switches from aching lyricism to robust demotic humour, its mesmeric mix of floating abstraction and earthy realism and its fluid structure which moves with a fine psychological expressiveness, between past, present and future.

This end-of-innocence drama involves a trio of childhood friends in their fraught last week of school. There's thoughtful, pacific Des, who has recently lost his mother; blustering, motormouth Joe, who's not nearly as streetwise as he'd like to think; and tomboy Danny, who, much to the resentment of Joe, is beginning to appreciate that Des has more to offer a girl than football practice.

The frustrations and deadly repetitiveness of life in an isolated seaside town ("the rest of the world could set itself by the way the day goes in this shagging place") come across keenly. To break the stifling monotony, the threesome have developed the daily high-risk ritual of diving into the sea off high rocks. The electric sensations of the vertiginous plunge ("flying through air and the cliff side tears past you like the pages of a book you're thumbing through too fast") are as viscerally captured in the writing as the momentary impression, when they hit the water, of ecstatic release from the dreary provincial round ("everything switches from black and white to colour... just for a split second, just long enough to show you what you're missing out on for the rest of the day").

But the three friends have also been paddling in the shallows of adulthood. They wind up frantically thrashing around in the deep end, when a series of individual humiliations converge on the penultimate school day and propel them on a face-saving trip to the city discotheque and a disastrous attempt at a drug deal. The production's pace and rhythmic variety (aided by a creepy sound design from Jim Turner) heighten the narrative tension in this gutsy, poignant chronicle of a tragedy foretold.

The excellent young cast do the piece proud, with Aidan O'Hare a hauntingly wistful Des and Kevin O'Leary's vivid Joe hopelessly struggling to disguise the naive, dependent schoolboy as an urban toughnut. Most arresting of all is Corinna Cunningham, whose powerful dumpy Danny can switch from having the look of a weird, crotchety misfit to assuming the glow of a strange, serene beauty and of ardent, piercingly misplaced hope. This actress will, I suspect, have a fascinating future.

Securing Blue's English premiere is a tribute to the Latchmere, a pub theatre which, under its new artistic director, Paul Higgins, has started to make waves. With work of this quality, it's not just devoted fringe-fanciers who should be keeping an eye on the venue.

To 7 Dec (020-7978 7040)