THEATRE / Just mad about the boy: Coriolanus - Swan, Stratford; Twelfth Night - Royal Shakespeare, Stratford; After Easter - The Other Place, Stratford; Arcadia - Haymarket; The Lodger - Hampstead

IT IS the word 'boy' that seals the hero's fate in Coriolanus. This is the ultimate insult that drives him to his last, suicidal assertion of manhood. In the case of David Thacker's production, it carries the added force that, in the midst of his stolidly middle-aged allies and enemies, Toby Stephens looks like a boy.

Maybe the young Albert Finney had the same effect when he took over from Olivier. But the standard image has been that of a seasoned warlord who happens still to be under his mother's thumb. You could thus cut the intolerable protagonist down to size as someone who never grew up. Present him as a boy, though, and there is no belittling immaturity. He cannot be explained away. He regains his mystery. You have to take him on his own terms as a killing machine who is also incontestably a tragic hero; and a political innocent who arbitrates over a political drama of inexhaustible prescience.

Thacker's production has a French Revolutionary setting (by Fran Thompson) with the armed figure Liberty framed in a smashed back-wall, and banners festooning the galleries where the plebeians gather for mass demonstrations. It is an apt analogy in the sense that both Coriolanus's Rome and revolutionary Paris occupy a republican Year Zero whose future is a blank sheet. Coriolanus's Gallic counterpart is obviously the young Napoleon, who spoke of dispersing the rabble with a whiff of grapeshot. The fact that one turned against his country and the other lived on to become its Emperor only reinforces the show's intention: to awaken a sense of alternative possibilities and acknowledge that a prodigious individual can sometimes derail the forces of history.

That is a cold description of a red-hot event. Compared to other recent versions of the play - from which it has emerged as a study of Realpolitik, or the manipulation of public opinion - Thacker's production has no particular case to argue. By the same token, it is also free from cynicism and bias. Every viewpoint is presented with maximum eloquence; every mean, private manoeuvre nakedly exposed. Your attitude towards the competing factions is continually rebounding between admiration and contempt. How should I describe Philip Voss's Menenius? A man who lives for his own comfort, or who wants to be on good terms with everyone? Both are true; and his mounting agony when he is forced first to take sides, then to grovel to his dearest friend, propels the show into the unexpected territory of bourgeois tragedy. There is an equally magnificent partnership between Ewan Hooper and Linal Haft as the Tribunes, weightily resolute men of the people, and also a scheming pair of skin-savers.

The arguments are well articulated, but contained within stage pictures that provoke a gut response. Famine, warfare, plenty: these are the mainsprings of human action, and they dominate the stage from the opening sight of doors slamming shut on the grain store, to the city gates closing on the blood-soaked hero. Vocally, Stephens is not yet on top of the role, and there are passages when he skates over the lines in generalised derision. What he does convey is a youthful sense of indestructibility magnified to that of a demigod. He has a fearsome opponent in Barry Lynch's smouldering, evil-eyed Aufidius. But you can dissect that performance. Stephens, permanently on heat for conflict with his cracked smile and quivering limbs, takes possession of the stage like a force of nature.

With its cute Warwickshire street scenes (John Gunter) and lush orchestral underpinning (Nigel Hess), Ian Judge's production of Twelfth Night has all the signs of a number one tourist attraction. It also overflows with fresh and truthful detail - beginning, if you please, with a comic Orsino (Clive Wood) whose pretended grand passion collapses in ruins once he meets Viola and experiences the real thing. No wonder, given Emma Fielding's performance, which combines the high romance of a bereaved castaway with a commanding comic attack - as in her peremptory treatment of Olivia (Haydn Gwynne) before submissively modulating into the praise speech.

Where you most expect comedy there are fewer laughs than usual. Neither Bille Browne's ostrich-like Aguecheek nor Tony Britton's over-gentlemanly Toby add much to these outlines, and their drunken party consists of stiffly rehearsed routines with not a drink in sight. But any comic team would probably be eclipsed by Desmond Barrit's Welsh Malvolio: an immobile, puddingy poseur, galvanised into a garter-snapping flasher, and then into a tragic clown, howling frantically in the dark. The show ends with the sight of Feste (an exquisitely melodious Derek Griffiths) being thrown out of the house to sing his last song under the night sky. For once, Malvolio gets his revenge.

Until half time, Anne Devlin's After Easter seems to be about Greta, who has renounced her native Belfast for marriage to an Oxford Marxist, and is now afflicted with Roman Catholic visions, for which she is confined to a mental home. Released for Easter, she joins her two sisters at the bedside of their dying father, and what began as a Celtic echo of Claudel turns into the Irish equivalent of a David Storey homecoming drama. In Michael Attenborough's production, the result is a frustrating combination of duty and pleasure. Devlin can write piercingly truthful family scenes ('Isn't this nice?' asks the mother, reunited with all her children, even though they are cowering under a table during a street raid); and she has a lovely vein of inconsequential comedy. Simultaneously, she feels obliged to pack every aspect of sectarian and Anglo-Irish strife into the family quarrel.

The work of a committed company is powerless to relieve the resulting congestion. Given Stella Gonet's rapt performance, you feel particularly cheated that Greta's story is left in mid-air.

In Simon Burke's The Lodger, a reluctant prostitute on the run from her violent pimp winds up in a Northern town as the lodger of a lonely policeman who beats her to a pulp. There may be a moral in there somewhere, but given the computerised dialogue and suspense tricks, I am not encouraged to dig for it. Philip Jackson and Julia Ford make something of the couple's probing overtures: the climaxes defeat them.

It may be pointless to recommend Tom Stoppard's Arcadia, now regally installed at the Haymarket after picking up its third award. But Trevor Nunn's new company (Julie Legrand, Joanne Pearce, Roger Allam) strike me as even more incisive than the original National Theatre cast. And the better you get to know this amazing piece, the more enjoyable it becomes. A glorious night out.

'Coriolanus': Swan, Stratford, 0789 295623. 'Twelfth Night': Royal Shakespeare, Stratford, 0789 295623. 'After Easter': The Other Place, Stratford, 0789 295623. 'Arcadia': Haymarket, 071-930 8800. 'The Lodger': Hampstead, 071-722 9301.