<preform>Ta Main dans la Mienne, Barbican Pit, London</br>Losing Louis, Hampstead, London</br>Bites, Bush, London</preform>

The magus makes more magic

If the Barbican frequently resembles the international departure lounge of high culture, then the frequent flyers are milling about outside the Pit tonight. I spot John Tusa, Paula Rego and ex-ICA boss Philip Dodd on my way in. Peter Brook himself, a smiling, smallish, silver-haired man, is at the centre of a press of well-wishers. What's in store from the legendary director, the pre-eminent magus of the modern stage?

If the Barbican frequently resembles the international departure lounge of high culture, then the frequent flyers are milling about outside the Pit tonight. I spot John Tusa, Paula Rego and ex-ICA boss Philip Dodd on my way in. Peter Brook himself, a smiling, smallish, silver-haired man, is at the centre of a press of well-wishers. What's in store from the legendary director, the pre-eminent magus of the modern stage?

Inside, the Pit has been half curtained off, and reduced in size. The acting area is unassuming, a low dais covered with an enormous faded carpet. There are three chairs; a table. The seating is raked in front, with a single row of chairs on either side. Two actors walk on, hand in hand, ignoring the audience member who is still finding her seat. They begin to talk. No drumroll, no drama: if this is theatrical magic, it comes from the very simplest components.

Peter Brook's Ta Main dans la Mienne is based on the letters of Anton Chekhov and the actress Olga Knipper, for whom he wrote some of his most resonant roles. They met at a reading of The Seagull, fell in love and married. But Olga's career in Moscow and St Petersburg, and Chekhov's self-imposed exile in Yalta, where he nursed his precarious health, meant they spent little time together. So they wrote radiant letters, and the title, "I take your hand in mine", was his regular salutation to her.

The first mystery is the age of the performers. Michel Piccoli and Natasha Parry, the latter a long-term Brook collaborator, would conventionally be too old to play these people at this particular time. Chekhov was only 44 when he died. They have been chosen for their prized Brookian attributes of lightness and grace, and that hard to define but unmistakable quality of being absolutely present in the moment. Piccoli's Chekhov, though clearly an invalid, is attentive (rather than alert), curious, amused - frequently crumpled up in laughter, in fact. Parry is far more than just his foil - she's his Aeolian harp, responding to every breath. Chekhov's uneasy relationship with Stanislavsky (Brook's fellow theoretician of the theatre) is amusingly outlined. Ignoring Chekhov's protests, "It's a comedy!", the director pioneered the slow, sombre style with which the playwright became associated. This evening is as much about theatre as it is theatre.

Brook's own programme note on Chekhov is suggestive. He describes going to the Moscow Arts Theatre to see Stanislavsky's 50-year-old production of The Three Sisters, preserved as though in amber. "I've the feeling that there were still some of the original cast - the oldest, of course in the youngest roles. I expected the worst, but what a splendid shock! To this day this remains one of my finest theatrical experiences," he writes. Aha! Clearly only a literalist dullard would cast actors who actually look like the people they're supposed to represent! But suddenly Piccoli's age and perceived fragility seem to be a marvellous metaphor for the younger man's mortal illness.

Chekhov's wise doctor, sensing the end was near, prescribed an injection and ordered three glasses of champagne. Piccoli, sitting in a chair, closes his eyes to represent the moment of death; then opens them, begins to talk again, then wanders off to sit by the side of the stage. The simplicity of this is deeply moving. Olga, alone, describes all she has left to live for, with a thrilling cry of "Théâtre! théâtre!" (The production is surtitled.) "Anton, where are you now?" she calls. The answer is, of course: he's here, he's all around us.

The play ends with Olga and Anton sitting side by side, his eyes softly flickering as he watches the descent of imaginary snow. From first to last, this was a spellbinding and instructive evening.

You have to feel sorry for anyone else opening in the same week as Peter Brook. What on earth would he think of Leaving Louis, a brash, cheerful farce, more suited to the West End than Hampstead Theatre? Tony and Reggie are two estranged Jewish brothers who both married out (Steadman and Lynda Bellingham are the wives). The men reunite after 10 years to bury their father, Louis. The action is split between the 1950s, with Louis juggling conjugal relations and an affair with his wife's best friend. As the Fifties characters go off, the Nineties ones come on in a blur of action. The burial takes place in the interval and is catastrophic. The second act deals with the fall-out (in both senses), when home truths and recriminations find their mark.

Steadman's Sheila, a priceless comic character, has come to the funeral with her eye on Louis's old grandfather clock, which we hear tolling offstage. Even the most unpromising conversational gambit can be turned to the subject of clocks. She's hilarious; only the most accomplished milkmaids can wring the udder this vigorously. Without this high-calibre cast, this play, charming though it is, could fall very flat. I hope Simon Mendes da Costa, the writer, is grateful to Mesdames Steadman and Bellingham.

Which leaves Bites at the Bush. I wish some of Brook's lessons would filter down to the fringe. As the audience comes in, actor Chris Jarman is already on stage, policing it in fact, sharpening a knife and scowling at latecomers. Then the ensemble sings "Catch a Falling Star" fortissimo. There's much eye-balling of the audience, gesturing, emoting and mee-mawing. It's a pity, because Kay Adshead's play of seven varied "courses" (scenes) is not at all bad. It throws into the pot lots of ideas about greed, aggression, meat-eating, colonialism, consumption, craving and denial - but then barely cooks them. "Hog Roast" features a memorably nasty barbecue, and the chilling "Ice Cream" transports us to Afghanistan under the Taliban. It's not a meal you'll remember for a lifetime, though.

'Ta Main dans la Mienne': Barbican Pit, London EC2 (0845 120 7550), to 12 Feb; 'Losing Louis': Hampstead, London NW3 (020 7722 9301), to 19 Feb; 'Bites': Bush, London W12 (020 7610 4224), to Sat

Kate Bassett is away