Oxford Street, Royal Court, Jerwood Theatre Upstairs, London

Levi David Addai's new play Oxford Street is dedicated "to all those who toil or have toiled in retail, particularly those who work on that mile-and-a-half high street in London W1". That sympathetic salute, like the lively detail of his mischievous, closely observed comedy, smacks of insider knowledge. It would be no surprise to learn that he has paid his dues temping in that neck of the woods.

The last time that Oxford Street and art could be cited in the same breath was in 2001 when Michael Landy took over a vacant department store and, in protest at consumerism, catalogued and destroyed all of his 7, 226 personal possessions. While there are times that Addai's frustrated young sales assistants must wish to inflict a similar fate on the stock they are paid to flog at Total Sport, the management suspects that they are all budding shoplifters. Hence the "new exit law" whereby staff members have to fill out a form to confirm that they have been searched on the way out. It's an innovation that gives rise to the moral dilemma facing Nathaniel Martello-White's likeable Kofi, a black Londoner and recent graduate who's in danger of getting stuck at the store as a security guard. Darrell (Ashley Walters), an old school pal and a cocky bad lot, joins the workforce and wants Kofi to switch off the alarm and turn a blind eye to his trolleyload of liberated goods.

Addai's gift for buoyant comedy and cheeky charm was evident in his highly promising debut play 93.2 FM, set in a South London community radio station – a drama animated by sharp banter and a wicked ear for street argot and stylised, slangy patois. Oxford Street likewise sweeps you into a distinctive, thoroughly realised world. This impression is enhanced, in Dawn Walton's bustling, punchily acted production, by Soutra Gilmour's design, which transforms the Theatre Upstairs into the Oxford Street branch of Total Sport. Perched on white plastic pods that look like embryonic toilet bowls, the audience sits in the thick of the action as it moves around the various locations, from the security office and staff-room to the patrolled front doors.

The playwright has had the bright, fertile idea of throwing the scapegrace, racially mixed, workforce into attractively comic relief through the perspective provided by Alek (hilarious Kristian Kiehling), a twenty-something Polish loss-prevention officer. Strapping, unbudgeably humourless, and a pedantic stickler for the rules, he sneaks mistrustful glances at his less dutiful colleagues over the top edge of his Daily Mail.

Kofi and Preeya Kalidas's lippy Loraina, a wannabe songstress ("I didn't choose to do performing arts, performing arts chose me") enjoy winding up this burly obstruction to slacking, parodying his prejudices by treating him to an earful of argot ("yunart'amean?!").

Addai has a lightness of touch and a natural ease with dialogue that are reminiscent of our best black playwright, Roy Williams. As yet, though, he doesn't have Williams's acute instinct for locating the painful faultlines in multicultural Britain. Like the problem of betraying one's roots through upward mobility in 93.2 FM, the moral question of whether or not to snitch on a "brother" feels a bit shop-soiled (so to speak) as a dramatic focus. The pleasure of Oxford Street lies in the bounce of the joshing backchat, the dexterity with which it juggles multiple situations, and the authentic feel of the relationships (Cyril Nri gives a lovely performance as the impatient but humorously good-natured security manager who takes a protective, avuncular interest in young Kofi).

Another major boon is the spry way the wit keeps springing surprises. Asked by the lonely, smitten manageress whether, in lieu of Father Christmas, there's a figure in Ghana who represents the Yuletide spirit, Emmanuel replies that, yes, there is. It is Jesus Christ.

To 31 May (020-7565 5000)