Blackbird, Albery Theatre, London

One role-reversal too many in this topical tale of child sex abuse

David Harrower's first and best-known play, Knives and Hens, was a drama of jealousy and a sexual power-struggle set in a sparsely drawn medieval society, and written in a language so austere and limited as to seem almost abstract.

In comparison, Blackbird, set in a recognisably 21st century British landscape and dealing with the perennially urgent subject of child sexual abuse, seems almost frantically topical: and, since its premiere at the Edinburgh Festival last summer, anxieties over teachers on the sex offenders' register have made it seem only more relevant.

Watching Peter Stein's production revived in the West End last night, though, the question arose of how far this new topicality is an illusion. The action takes place in the functionally furnished, garbage-strewn locker-room of a manufacturing company on an industrial estate somewhere in Britain (nicely realised by Ferdinand Wogerbauer's set).

Here, Una, a woman in her late 20s, confronts Ray, the man with whom she had a sexual relationship years ago, when he was 40 and she was just 12.

At first, he assumes that she is seeking vengeance, or closure or some such but it soon becomes clear her motives are far more complex - indeed, that for both of them their former relationship was much more complicated than a simple dichotomy of abuser and victim.

She, she assures him, wanted and valued sex with him; he, for his part, has never had sexual feelings for any other girl that young.

Would it make sense to call their relationship an affair? To say that they were in love? It would be too easy to call Harrower's play "challenging": he is never that direct. Instead, he creates an uneasiness about the categories we impose on relationships, an anxiety that our vocabulary is rarely up to the job.

The two actors, Jodhi May and Roger Allam, are both assured and disconcertingly changeable - to begin with, she oozes sexual confidence and righteous indignation, while he is all constraint and anxiety. But as the action develops, the roles are time and time again reversed, up-ended, mutated.

If anything, roles are reversed rather too often: towards the end of its unbroken two-hour span, the play starts to feel a little random and repetitive, and you wonder quite where it is going.

May gathers up her coat to leave once or twice too often and while a late-arriving plot-twist confirms that Harrower isn't trying to replace the audience's easy certainties with certainties of his own, it also feels slightly effortful.

In Peter Stein's production, a final tableau shows Ray and Una wrestling in a car park (complete with real car, and real exhaust fumes).

It seems startlingly clumsy for a director of Stein's international status, and considered purely as spectacle it is ludicrous but it does serve to pull the focus back a little, clarifying and broadening the play's purpose: it's about the way that any sexual relationship can be shadowed by abuse and collusiveness.

Harrower, it seems, is still ready to tackle the same timeless questions.