That Face, Royal Court Theatre Kiss Of The Spider Woman, Donmar Warehouse, London

Dominic Cooke, the Royal Court's artistic director, promised to take us from the theatre's usual council estates to the purlieus of the bourgeoisie - and, indeed, the characters in That Face inhabit an expensive London flat, a Hong Kong house and a boarding school, and have accents to match.

Otherwise, however, it's the mixture as before - mother a slave to drink and drugs, one teenage child a criminal, the other a mess. But in the most important area - the quality of the writing - there is a distinct improvement. The dialogue is lively and authentic, the psychology astute, and the mood varies from pathos to bitter comedy - all the more remarkable since this is Polly Stenham's first play, and she is 20 years old.

Sent home from school in disgrace, Mia walks in on a brother who has abandoned his own school to be his mother's keeper. Mum herself is badly hungover, and resents the intrusion of a daughter she sees as competition for the time and affection of a son who is her teddy bear, servant and substitute husband.

Stenham's ear for the bravado, anger, and self-justification of this sad trio is acute. She shows us that the girl's malice and manipulation are her way of seeking power to replace the love she's been denied. She lets us see the child who suddenly peeps out of the ostensibly mature young man.

Much of the success of That Face, however, is due to Jeremy Herrin's beautifully directed production and its luxury cast, including Lindsay Duncan as the mother and Julian Wadham as her former husband, just off the plane from China to take charge, and full of smooth corporate clichés. Both are eerily, sickeningly realistic, as are Matt Smith as Henry and Felicity Jones as Mia. But, though there is some welcome amusement in Duncan's flirtation with the speaking clock, the tone is close enough to Noël Coward's to remind us uncomfortably of The Vortex. And, while it is morally proper for all our sympathy to be with the children, it is dramatically monotonous.

You could say it's just a bit schematic: outrageously camp homosexual and stern, straight revolutionary share a prison cell in the Argentina of the Seventies. Gay man, a stool pigeon for the jailers, tenderly nurses sick rebel and tells him, for a bedtime story, the plot of an old movie about love, death, and transformation. The rebel unbends, giving his cellmate sex and affection, and the other takes on the ideals of his friend, but the transformation wrought by love ends in death.

When Manuel Puig's novel was written, it was notable for its bravery in attacking his country's fascism and showing a despised type as heroic. Now the plot's predictability is obvious, and is emphasised by the author's adaptation (very well translated by Allan Baker), which simplifies the story even more.

Will Keen's Molina talks in a high, mechanical voice, wears an embroidered pink kimono, and, with his abrupt, swerving hand gestures and little dips and bobs, is a kind of robot geisha. We are told that the rebel, Valentin, is in his late twenties, but he seems, as portrayed by the floppy-haired Rupert Evans, much younger and, unlike the character in the novel, jittery and vulnerable from the start. Hardly the strong man of Molina's fantasies, this Valentin does not appear to be a likely holder of important secrets or a great sexual challenge.

More predictable stories than Puig's have been redeemed by passion, but not this one, this time.

'That Face' to 19 May (020-7565 5000); 'Kiss of the Spider Woman' to 26 May (0870 060 6624)

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