THEATRE / Back to ABC in the Tower of Babel: Pentecost - The Other Place, Stratford; The Green Parakeet - Greenwich Studio; August - Theatr Clwyd; The Prime of Miss Jean Brodie - Strand; Gaucho - Hampstead

IN 1990 David Edgar joined in the revisionist stampede of left-wing playwrights and produced The Shape of the Table, a premature and unconvincing conversation-piece on post-Communist Europe. There is nothing premature about his new, and equally topical, piece, Pentecost, which follows in the shattered aftermath of that false dawn. It is the richest text to arrive on the English stage since Stoppard's Arcadia; and a drama on the politics of language that ranks with Friel's Translations.

At its centre, unusually for Edgar, is an art object: the remains of a 12th-century fresco discovered in an abandoned church (and former torture chamber) somewhere on the east European border. The name of the country is unimportant; what counts is that it is a place that has somehow preserved its national identity through centuries of neighbouring invasions. Edgar declares his linguistic theme in the opening exchanges between a primly pedantic British art historian (Charles Kay) and the local museum curator (Jan Ravens), who peppers the details of her discovery with phrases like, 'I should cocoa]' What she thinks she has found is a pieta that introduces the techniques of perspective and individualised emotion a century before Giotto, which, if true, would locate the origins of the modern world in this Balkan Hicksville.

For her, the fresco promises a huge gain in self-respect for her downtrodden country. But it means different things to different people, and becomes a magnet for their competing interests. The Orthodox and Roman Catholic churches are already staking claims, followed by an American academic, Leo (irresistibly reminiscent of David Lodge's Morris Zapp, in Linal Haft's boorishly erudite performance), who is engaged in a crusade against art restoration.

Under the supervision of a flashily americanised Minister for Conservation (Glenn Hugill), the action flares into a fierce debate on the authenticity of the painting, and whether it should remain a devotional object or begin a new life on the museum circuit, a godsend to tourism. At which point, Edgar abruptly raises the stakes by turning the play into a hostage drama. A group of stateless refugees storm the church and issue an ultimatum demanding Western citizenship, whereupon the fresco acquires yet another leading role, surpassing the hostages as a bargaining chip. In the end, this being 1994, the refugees get nothing, and (on the orders of the Minister) the fresco is reduced to rubble.

With its central gear-change and polyglot double cast, you might expect the play to sink under its own weight. Given Edgar's decision to track the art-versus-human life argument to its limits, there was no avoiding narrative complication. But what emerges from Michael Attenborough's superbly cast production is a passionately well-informed international work, held on course by a governing idea: the eternal recurrence of the Tower of Babel.

This idea not only underpins the dialogue (mostly written in English as a Second Language); it also crops up in echoing details, such as a terrible story of starving children eating their own name-tags, reflecting the fact that restoration of the fresco would mean erasing the signatures of torture victims. The play ends with the chastened Leo and the curator exchanging simple words out of a book. Perhaps if mankind re-learns its ABC, it may start getting things right.

During the Cold War, Schnitzler's The Green Parakeet was a favourite on the Czech stage, and in Margarete and Julian Forsyth's version this 1898 masterpiece proves itself as timely as ever. Set in a Paris tavern on the eve of the fall of the Bastille, it is also the ultimate pub-theatre play.

Here, under the direction of a thespian landlord (Bill Stewart), actors play criminals and revolutionaries for audiences of aristos, who delight in being insulted and threatened in the supposed name of radical chic.

Within this framework, Schnitzler weaves an amazing series of meta-theatrical variations. A real murderer (Eddie Marsan, evoking Peter Lorre), engaged for a homicidal role, is dismissed as unconvincing by the leering connoisseurs. A devoted married couple perform a pimp-and-whore routine. A villainous anti-royalist breaks down in mid-tirade, driving the landlord to moans of despair at the artistic shortcomings of his troupe.

Then comes the news of the mob's triumph; and, with a wonderfully plotted climax, the game turns into reality, with the result that the Green Parakeet -like satire houses all over post-1989 eastern Europe - is out of business.

Deploying a violently active company of 17 in a pocket stage, the show is also a directorial triumph.

The alliance between Anthony Hopkins and Theatr Clwyd is plainly a love match, but its first offspring - August, Julian Mitchell's Welsh adaptation of Chekhov's Uncle Vanya - offers small reason for celebration beyond its benefit to Clwyd as a house-filling star event. What it proves is that however successfully Chekhov adapts to Ireland, he remains a stranger in Wales. References to the Band of Hope and characters marrying outside the chapel strike no answering Russian chord; and most of the Welsh detail is lavished on servants and retainers, leaving the principal figures unchanged.

The one exception is the ineffably languid Helen, whom Mitchell converts into an American child bride (Lisa Orgolini) who is always running about the place. Only Hugh Lloyd, as the lugubrious mouth-organ playing 'Pocky' Prosser (alias Telegin) achieves a performance that is both Welsh and Chekhovian. Leslie Phillips effectively turns the visiting professor into a figure of fun, forever trumpeting his hatred of Wales. Other principals in Hopkins's production are seriously undercast.

As Ieuan (Vanya), Hopkins has an arresting first entrance: a crumpled, rolling figure, drink in hand, making several false starts at lighting a cheroot, and then drowning out Pocky's domestic confessions with a raucous chorus of 'Bread of Heaven'. You want to know what he will do next. He is unpredictable and dangerous. And before long, he has coarsened into a sardonically aggressive oaf, whom you cannot imagine as a dutiful estate manager. In short, he is not the disenchanted idealist of whom Chekhov said, 'He wears marvellous neckties'. As Astrov, Hopkins might have been magnificent: Vanya is not his role.

The Prime of Miss Jean Brodie, Jay Presson Allen's adaptation of the Muriel Spark novel, returns as piercingly funny as ever in Alan Strachan's revival.

New to me is the contrast between the gym-slipped Brodie set and their inspiring teacher. Where you see the girls (look out for Jackie Morrison and Liz Ewing) picking up experience at high speed, the fascist romantic heroine -in a peach of a performance by Patricia Hodge - emerges as an incurable innocent.

Based on the career of Howard Marks, the Balliol drug baron, Doug Lucie's Gaucho shows a millionaire Oxbridge pusher, Declan, entertaining a pack of old cronies in his Aegean hideaway so as to prove that even his activities are morally superior to those of British MPs, journalists and businessmen.

Tim McInnerny plays him with style: and despite Lucie's Socialist credentials, you are left to the right-wing conclusion that whatever Declan does is OK because he has breeding. A sour and disingenuous piece of writing, very well performed.

'Pentecost', The Other Place, Stratford, 0789-295623. 'The Green Parakeet', Greenwich Studio, 081-858 2862. 'August', Theatr Clwyd, 0352 755114. 'The Prime of Miss Jean Brodie', Strand, 071-930 8800. 'Gaucho', Hampstead, 071-722 9301.