It's the Holocaust play if you're a Jew, or the dead child play if you're a parent. These are plays that are particularly hard to watch if you are a member of a certain demographic. It's not that, as subjects, the death of children or genocide is only of interest to the potential victims of such events. But if you are a parent you are bound to be haunted by the possibility of a child's death in a way that non-parents just aren't. And the same is true of Jews and genocide.

My point is that there is an extra responsibility - or burden - on any playwright attempting to broach such subjects as emotive as these. They must avoid what David Lindsay-Abaire, the American writer of this dead child play, calls "grief porn". And, to that end, his script, which focuses on a couple whose four-year-old son Danny was killed by a car when the boy chased the family dog into the road, is a complete success.

A lesser, and less funny, writer would have wallowed in the breast-beating, soul-bearing agony of it all. But Lindsay-Abaire is much more subtle. His play, which begins eight months after the accident, steps in time with the domestic rhythms of what is, but for the lost son, a normal household. Becca (Claire Skinner) is seen ironing some clothes; Howie (Tom Goodman-Hill) comes home from work and watches TV.

Viewing the comings and goings of this home is a little like watching a concert where all music has been extracted leaving just the beat of a metronome.

And then it emerges that the clothes being ironed belong to an unseen little boy and, on TV, Howie is watching home videos of his laughing son. It's this close observation that has such potency. For the viewer, there are scenes here that can reach through the chest wall and squeeze the heart till its dry.

In Edward Hall's beautifully acted production Skinner and Goodman-Hill are as understated as Lindsay-Abaire's writing. They get superb support from Georgina Rich as Becca's plain-talking sister, Penny Downie as their clumsily loving mother and Sean Delaney as the guilt-ridden young man who was driving the car that hit Danny.

Yet for any parent already haunted by the possibility of being vaulted into Becca and Howie's world, there has to be some intellectual payback for being put through the emotional wringer. True, the portrayal here of a once-close couple, now separated and isolated by their grief, is a thing of rare nuance. For Howie, evidence of Danny's existence is a comfort. For Becca the boy's toys and fridge paintings trigger yet more torment, not made no easier by the news that her sister has become pregnant.

But there is nothing here about this particular kind of grief that those who fear it don't already intuitively know. It is, I hesitate to say, more for those who don't have children than for those who do.