DAVID Harrower's play, Blackbird, has been making a name for itself ever since it opened at the Edinburgh International Festival in 2005. It caused a stir then and it is still unsettling theatre-goers in its current run at the Project. It has also just won the Olivier Award for Best New Play.

Blackbird deals with one of the few remaining taboo subjects in our society, the sexual abuse of a child. The play opens when the two protagonists, Ray and Una (superbly played by Stephen Brennan and Catherine Walker), meet 15 years after they had a sexual relationship. At the time, Una was 12 and Ray was 40.

The play is set in Ray's workplace canteen, a filthy kitchen with rubbish and discarded food strewn around the floors and tables. The effect is all the more seedy thanks to Sinead McKenna's perfect recreation of particularly grim office lighting.

Ray makes a half-hearted stab at clearing some of the rubbish.

"Do people just expect other people to clean up after them?"

he asks, a reference, of course, to what happened between him and Una, and the mess her life seems to be in now.

While Ray was convicted, after serving his term he moved away, changed his name and started a new life, complete with new job and girlfriend. Una, on the other hand, has struggled to come to terms with the abuse. If anything, her life has been defined by it . . .

her family never moved away from their home and her neighbours knew of what happened. When she accidentally uncovers Ray (now living life as 'Peter') 15 years later, she seeks him out and confronts him.

It is a disturbing play to watch and often the characters' reactions are not what you might expect. Ray is not always remorseful and is outraged that Una has sought him out.

Una on the other hand can sometimes appear uncomfortably kind in her attitude to Ray, and at other times justifiably angry.

Issues of blame and shame are dealt with here. Una's mother blames her precocious daughter for the abuse and the judge in the case referred to Una as having "suspiciously adult yearnings".

Harrower poses difficult questions, especially in this area of "provocation". Does the fact that Una had a crush on Ray and sent love letters to him as a child exonerate him in any way?

This is a gripping play, not just because of the way the subject matter is explored, but because of the complex questions raised about the characters.

Blackbird is an unsettling story, all the more so because of Harrower's refusal to take sides between Una and Ray. That, combined with a final twist in the story, makes for a disturbing but compelling play.