Woman And Scarecrow, Royal Court Upstairs, London <!-- none onestar twostar threestar fivestar -->

Propped up on pillows, an unnamed, dying Irishwoman - the mother of eight and the wife of a faithless husband - is full of regret for a life she has failed to live to the full. Prowling around, berating her about mistakes and missed opportunities, is her alter ego, referred to as Scarecrow. There is also something horrifying trying to get out of the wardrobe, and Scarecrow's efforts to keep it at bay appear increasingly doomed.

Watching a deathbed drama set in winter might seem a morbid way to spend an evening in high summer. Yet you emerge from Ramin Gray's excellent production of this new Marina Carr play feeling energised rather than depressed. The dramatist's lyrical intensity is here offset by a lively streak of gallows humour. Her vision of imminent death is comically alert to how pettiness and unfinished business keep getting in the way of the high romantic exit. It's a galvanising work because there is nothing defeatist in the fierceness of its regret.

By turns wittily exasperated and despairing, offhand and harrowed, Fiona Shaw's superlative performance brings out all the contradictions in the Woman. She's both vain and self-mocking (ogling herself in a mirror, she notes, "Now, finally, I have achieved bones... Look at me! I am graveyard chic").

She seethes with resentment at her husband (Peter Gowen), and can't stop loving him. She has led a passionate life, but only in the Latinate sense where passion is equated with suffering. From her current perspective, she sees happiness as an "easy... decision. Like going to the dentist", which we foolishly resist making. On the other hand, she believes that it's a condition of life that we feel alienated from our true selves. With an aria from Dvorák's Rusalka underscoring the speech, she compares our plight to that opera's water-nymph, who prays to be made human so that she may achieve love.

Brid Brennan's wonderfully beady Scarecrow represents the more analytic and vindictive side of the Woman, while Stella McCusker's sternly solicitous Auntie Ah is a blackly comic incarnation of Catholic repression. The piece owes quite a bit to Beckett, while wholly lacking his economy, and the deployment of the alter ego recalls similar uses of the device in Edward Albee's Three Tall Women and Tom Murphy's Alice Trilogy, seen last year at the Court. But Woman and Scarecrow is far more than the sum of its influences and soars into own wryly magniloquent singularity.

To 15 July (020-7565 5000)