A Conversation, Royal Exchange Theatre, Manchester

It's hardly a conversation, more a sequence of revealing monologues, some very angry, emotional dialogue and an uncomfortable exploration of the limits of moral obligation. In the riveting British premiere of A Conversation, by the Australian writer David Williamson, two families face each other across an impersonal room. One couple, the Milsoms, have lost their only child at the hands of Scott Williams, a sociopath addicted to brutal sex. Opposite them are Scott's bewildered mother, younger brother, baffled uncle, and sister Gail, who, against all odds, has got herself through university and is now a political policy adviser. Added to this potentially explosive mix is the uptight psychiatrist who had previously recommended Scott's release into a system ill-equipped to deal with the administration of parole.

Williamson's tense drama, which takes the form of a painful community conference, offers a penetrating look at a restorative justice process that aims to bring balm to the wounds felt by those closest to both victim and perpetrator. Australia may claim to be "the nearest thing to a classless society on God's earth", but the deep divisions between the Milsoms and the Williamses resonate well beyond the factors contributing to this tragic event. "They're just going to unload on us again," fears Gail, and at first it seems she's right.

A taped message from the murderer, offering his regret and claiming that it was never his intention to kill the girl after sadistically raping her, fuels the heated atmosphere. The boy's mother requires the Milsoms' agreement to have her son put into protective custody to preserve him from another knifing in prison. Some hope, it seems. Derek Milsom would be happy to put a gun to Scott's head and shoot him, while Gail suspects he'd be happier hanging her brother by the neck with piano wire. Mrs Milsom wants Scott's mother to comprehend her pain. We certainly can, even without the graphic description, read out by her father, of the horrific injuries sustained by his beautiful daughter.

Each gradually admits guilt for some degree of deliberate omission that might have changed the course of events. So the moral emphasis shifts intriguingly towards what the characters did not do.

In Jacob Murray's sensitive production, which rides the switchback of raw emotion without diminishing into sentimentality, every member of the cast contributes magnificently and movingly. Their body language and varying degrees of eye contact reveal as much as their words. But rather too many statistics are bandied about, especially between the pedantic Derek and earnest Gail. Her final little lecture to Derek on the failure of government to make provision for the underprivileged and the greed of corporate executives is one lesson too many.