THEATRE / The Greeks had words for it, we don't: Thyestes - Royal Court, Upstairs; The Nun - Greenwich Studio; His Lordship's Fancy - Gate; Eva and the Cabin Boy - Croydon Warehouse (CORRECTED)

CORRECTION (PUBLISHED 19 JUNE 1994) INCORPORATED INTO THIS ARTICLE

LUCIUS ANNAEUS SENECA last graced the London stage in Peter Brook's 1966 production of Oedipus, which contained the characteristic spectacle of Irene Worth, as Jocasta, skewering her womb on a gleaming bronze spike. That was during the Vietnam war. Now comes Seneca's Thyestes, a story evidently too much even for the Greek dramatists, in which Atreus, King of Mycenae, welcomes his treacherous brother home from exile with a banquet at which Thyestes eats his own children.

The piece is modestly described as 'translated by Caryl Churchill'. It is not an original work. Compared with E F Watling's metrically resourceful Penguin version, it is not even an ambitious translation. There are some sardonic anachronisms and a tipsy blues for the sated diner; otherwise Churchill (last seen as a fancy stylist in The Skriker) limits herself to putting things as clearly as possible in prose that draws no attention to itself. It is her choice of text that matters, not any chances it offers for literary display.

James Macdonald's production is equally modest. The audience arrives to a sound of slurping body juices and tearing metal. But once the Ghost of Tantalus arises through a trap, begging for a speedy return to the Underworld where he will be safe from the human race, there are no more sensational effects. There is a bare, dark room with three monitor screens, and a casually dressed company who seldom raise their voices. They are there to speak the words with precision and occasional irony; not to embody these monsters or work the audience up with rhetoric.

The effect is cold-bloodedly illuminating: as where Kevin McMonagle's Atreus declares that public fear and lies are the proof of successful kingship. Occasionally you witness the events through the characters' eyes: when Thyestes (Ewan Stewart) apprehends the horror to come, the monitor images of the feast start swaying in nauseated sympathy. But apart from such small scenic concessions, the show depends entirely on the text to evoke the unspeakable.

The message I take from this is that Shakespeare and the Greeks are too good for us under the new barbarism of the 1990s. We cannot begin to find our own words for this; and if the theatre is to reflect it at all it may be through the dehumanised brutality of the Roman theatre in which fiction is killed by fact. This is a small show; but it is a portent.

At the Greenwich Studio, a suite of plays from the European Enlightenment ends with Julian Forsyth's adaptation of Diderot's The Nun. It is a feat. The book originated as a practical joke, intended to lure an old friend of the author's back to Paris; but once launched on the account of the outcast Suzanne's attempts to escape the cloister, Diderot (with personal memories of monastic confinement) was reduced to tears by his own sob story. The production reverses this creative sequence: following the heroine's ordeals from religious imprisonment to destitute freedom, and then allowing Diderot to stick his head through the canvas and turn Suzanne back into joke.

It is this risky manoeuvre that proves the quality of the show. A sentimental melodrama about wronged innocence would not have survived it. But Suzanne (a gentle, iron-willed Sharon Small) and her enforced companions are too well established to have the carpet yanked from under their feet. The heroine undergoes some harrowing cruelties; but the main, down-to-earth point is that she has no vocation and is bored to death by convent life.

The fact that Diderot is championing individual choice, rather than attacking the church, enables his clerical figures to develop lives of their own: in particular the contrasted succession of convent Superiors, culminating in Tessa Worsley's lesbian Reverent Mother, whose line, 'I'm a kind woman, don't make me act out of character', both stirs your sympathy and chills your blood. This is a fable that applies to every form of institutional compulsion. Margarete Forsyth's production makes cunning use of the Studio's shallow acting area, and extracts a rich variety of atmosphere and individual character from an identically clad company.

The Gate, meanwhile, completes its own 18th-century season with the British premiere of Goldoni's His Lordship's Fancy, featuring another disinherited girl. There all resemblance ends; any convent with designs on Sophie Okonedo's fire-breathing Rosaura would soon be reduced to smoking rubble.

Outside the theatre, my heart sank at the sight of a pair of commedia rustics advertising the fun within; and then leading off with torrents of organ- grinder Italian, and chases through the audience. I was wrong to be put off. These are preliminaries for the ceremony of welcoming the village's new lord and master, Florindo: a lecherous minor, who mistakenly believes that his title to the estate includes possession of all its women. As it turns out, he is entitled to nothing.

After its raucously slapdash opening, Paddy Cunneen's production gathers confident focus with the arrival of the reception committee and the substitution of Vivaldi for the village band. This is a serious comedy. What it shows is the transformation of a pack of provincial clowns into an instrument of formidable power when their civic rights are threatened. Rupam Maxwell does his stuff as the brattish overlord; but the real acting credits go to Dominic McHale and the other villagers. It is like seeing Dogberry & Co turning into the Three Musketeers.

In Eva and the Cabin Boy Sheila Dewey recounts the story of the last sailing clipper (the Lochard), wrecked off the Melbourne coast in 1876 leaving only the eponymous survivors. We see Tom saving the genteel Eva's life with brandy and the warmth of his body. This elemental situation turns to acid comedy when the pair are rescued, and the act of salvation becomes twisted into a question of sexual compromise with a class inferior. Dewey explores this absurdity with a Whartonesque sense of blinkered etiquette. She is brilliantly served by Karen Woodley and Tamblyn Lord as the misallied partners.

'Thyestes': Royal Court, Upstairs, 071-730 1745. 'The Nun': Greenwich Studio, 081-858 2862. 'His Lordship's Fancy': Gate, 071-229 0706. 'Eva and the Cabin Boy': Croydon Warehouse, 081-680 4060.