Constellations, Theatre Upstairs, Royal Court, London

Not since Mike Bartlett's Cock, so to speak, have I been so exhilarated by a new play premiered at the Royal Court's Theatre Upstairs.

As I sat through the extraordinary 65 minutes of Nick Payne's Constellations -- performed with uncanny brilliance by Rafe Spall and Sally Hawkins -- this sense of slightly incredulous elation was accompanied by the sinking feeling that, as a critic, one would be hard put to begin to do justice to the dazzling way it creates it own rules, while at the same time being wise enough not to jettison the old rule book either.

Cubist visual art crunches together many moments in time within the instantaneous stillness of a picture. Here it's as if a magic wand has been waved over such a work so that it comes alive, the multiple variations elapsing elastically in the constantly re-angled present tense of stunningly well-deployed stage time.

That description, though, might, misleadingly make the piece sound like hip, updated J B Priestley or Ayckbourn, both of whom have explored the dramatic power of flirting with the the alternative possibilities implicit in every moment. A smartass wag might jest that Payne does not understand the dramaturgical principle of draft-exclusion or, to put it slightly more positively, that he has a strong susceptibility to drafts, given the purposeful prevarication of Constellations and its refusal to discriminate amongst the host of hypothetical variants through which the couple in this two-hander travel. The wag would be wrong.

There are two things that, to my mind, make the piece work on your pulses as well as on your synapses. One is that the link with quantum multiverse theory comes across as deeply felt, unlike, say, the shallow, opportunistic use Charlotte Jones made of string theory in the very overrated Humble Boy. The second is that real pain (no pun intended) seems to be dragged like barbed wire through the guts of these often hilariously juxtaposed variations.

Yes, but who are these people and what do they do and say? I'm loth to reveal too much because I don't want to spoil it for you. It involves bees, barbecues, picking people up at dance classes, brain tumours, dialogue that develops the haunting quality of a refrain in a story told of out of sequence again and again. Staged on a central, hexagonally tied rectangle, Michael Longhurst's superb production (how on earth did they rehearse this?) features two performances that are miracles of timing as they dart in and out of knowing inverted commas and effect subtles glissade between beautifully calculated in-on-the knowingness and nakedly unfeigned feeling. There are little lapses from its own high standard but a wonderful achievement all round.

Until 11 February