THEATRE / Guilt edged: Paul Taylor on Daniel Magee's Paddywack at the Cockpit

Middle-aged, working-class Express reader Brian (the excellent Brian Croucher) is a cockney wind-up artist of sledgehammer subtlety but goading tenacity. There's nothing he likes better than making the middle-class liberal heart skip a beat. So, when there's a new lodger expected at their Kilburn digs, he tells fellow tenant Colin, a student slumming it there to impress his girlfriend, that the new bloke is something beginning with P.

Jumping to the conclusion that he means 'Paki' rather than 'Paddy' is not exactly going to prostrate Richard Trahair's well meaning, weedy Colin, but it sure as hell rattles the Irish Michael (Michael O'Hagan), whose feelings are summed up in the following sublime category-confusion: 'You heard me say how well Red Rum runs, but I don't want him in the next shaggin' bed to me.' The fact that the new arrival is Damien, a young man from Northern Ireland, comes therefore as quite a relief all round, but one which is very short-lived.

Watching Paddywack, Daniel Magee's compelling play, you may be reminded at points of Gogol's Government Inspector. There's the similar idea of a newcomer playing up to the false identity projected on to him by the locals; except that here, aided by a superbly enigmatic performance from James Nesbitt as Damien, the play leaves the audience guessing as well, until the violent, sickeningly 'logical' end is too close to be avoided.

Setting the central situation at a time of pre-Christmas IRA bombing, Magee delivers a wily display of the operations of prejudice. Erotic subtext is adroitly conveyed in Michael Latimer's powerful in-the-round production in scenes that show Damien using his reputation for Republican activism to seduce Annette (Holly Aird), Colin's sexy right-on girlfriend. By a neat irony, Damien commits what the prejudiced claim to be the classic crime of the immigrant: taking the women and the jobs.

Considering it is crucial to his final abashed revelations, Damien's switch from lust to love for Annette is under-dramatised. There is also a slight discontinuity between the guilty, deflated man who confesses to being ordinary and apolitical and the youth we have heard speechifying about the guilty-until-proved-innocent questioning his nationality automatically invites, and about the perverted sense of guilt, borne of years of repression, which makes an Irishman like Michael feel he's got to be seen at the head of the hang 'em brigade.

Listening to his passionate discourse, you may be in danger of forgetting that there are times when a question like 'Are you a supporter of terrorism?' simply has to be asked, regardless of its possible insensitivity. In general, though, this is a play that opens up debate and gives you a bracing mental work-out. It is often very funny as it shows you how the bigoted keep having to shift ground to defend their prejudices. And in Brian it creates a monster with a little of the troubling theatrical appeal of an Alf Garnett.

'Paddywack' is at the Cockpit, NW8. Booking: 071-402 5081