TWO people confront each other across a strewn space. It is a staff room and litter is everywhere, overflowing from bins, scattered across tables and fallen on to the floor.

The man is older, heading towards 60 perhaps; the woman much younger. The tension between them is so palpable you can feel it, especially from the woman, whose body twitches with antagonism; mouth tight, fingers clicking, she seems to be unresolved argument made furious flesh. And we are all there to watch, inches away, feet among the litter if you have a front-row seat.

Ray (George Costigan) might or might not manage this factory or whatever it is: certain details remain uncertain in David Harrower’s emotionally wrought two-hander. Una (Charlie Covell) is the intruder here, or so it seems, but this drama constantly plays with your expectations, and never takes sides when blatant partisanship would have been an easy position to hold.

For Ray is what some people would describe as a paedophile, although the word is not used, and he himself says that he was “never one of those”. Una has tracked down Ray, who is called Peter now, having changed his name after serving his sentence.

It is perhaps almost banal to say that both of them have served a sentence, although only one has been inside: yet that is what this shocking drama feels like, the living out of something that happened a long time ago, but in a sense has never stopped occurring, or at least reverberating.

Harrower waits a while, ten minutes or so perhaps, before revealing his play’s core: Ray slept with Una when she was 12 and he was 40. A trial followed, scandal ensued, and then each participant tried to put a lid on what had happened; unsuccessfully, as we are now seeing, all these years later.

This plays tackles a taboo subject without passing judgement; no one is condemned or condoned. Instead, the viewpoint changes depending on who is speaking, who is remembering what. The result is a drama that is shockingly claustrophobic, especially as tightly directed by Katie Posner in the small Studio space, and one which by turns shows different sides to a relationship, if it can be called that, which contained desire on both sides. There is, all these years later, anger too, a hellish lot of anger, and yet in fleeting moments a lost, puzzled sort of tenderness – a what-might-have-been emotional confusion stirred by a love that never should have been.

Harrower doesn’t tell us what to think, he avoids lecturing, which would have been the obvious, uninteresting thing to do. Instead, he displays a wrestling match of the emotions, alongside a study of the power of memory, and the soluble nature of truth.

Costigan is a picture of exhausted anguish as Ray, while Covell is twitching, coiled, sprung. Watching them is mesmerising, but not in a comfortable way.