THEATRE / On her metal: Paul Taylor on Diana Rigg in Jonathan Kent's striking Medea at the Almeida

ONE OF the principal ways that Jonathan Kent's powerful production of Medea is likely to live in the memory is as the sound of bashed metal. Peter J Davison's set locates Euripides' tragedy before and behind a huge wall of rusty, sliding panels that put you in mind of some derelict battleship. As the play proceeds along its harrowing course, these plates take quite a battering. When, for example, she confronts Jason, the husband who has brought her to Greece and then deserted her for another bride, Diana Rigg's riveting Medea pounds the metal, in what sounds like an unnerving variant of those bongs on News at Ten, to give outraged emphasis to each of the deeds she recalls having done for him: killing the dragon that guarded the golden fleece; deceiving her father; causing the horrible death of his uncle, etc. In a tit-for-tat parody of her percussive anger, Tim Woodward's sneering, defensive Jason gives the metal mockingly dainty little thumps as he itemises his reasons for believing she got more than she gave (principally, she was able to leave a barbarous homeland for civilised Greece). His action is an unsavoury, inverted flaunting of what he regards as his superior male strength.

By happy coincidence, two of Euripides' great revenge heroines have hit London at the same time (the other being Hecuba at the Gate, which was reviewed here last week) and both are brought to life in tremendous performances. Where the enslaved, sorrowing Hecuba begins as an object of reverent pity, becomes alienatingly warped by grief, and ends up butchering her enemy's children, Medea is a discomfitingly ambiguous victim / villain figure from the start and she is driven to the more shocking murder of her own little boys, though rescued from retribution by her grandfather, the Sun.

Hair tied back in a plait, her rigid face parchment-pale over blood-red dress, Rigg magnificently communicates the fierce, touchy pride of an alien who would rather bring down everything than tolerate the scorn of those she hates. She has burned all her bridges for Jason, so where else can she go? On the other hand, she has brought banishment on herself by making threats. There are glints of black comedy in the performance when Rigg brings out Medea's snobbery (how can Jason have thrown over the Sun's granddaughter for a girl whose ancestor was Sisyphus, she asks with superb snootiness) and she manages to signal the hurt, spurned wife without at all underselling the hard, calculating side of the heroine.

Violently torn between maternal love and the desire to cause Jason maximum pain, Rigg's Medea suddenly registers with a wonderful, sickened calm the fact that all the agonising is pointless. Her sons are as good as dead because of what she has already done; she must therefore kill them before her enemies. The most impressive feature of the heroine and of Rigg's splendidly unsentimental portrayal is that she makes no attempt to disguise from herself what it is she is pervertedly up to. 'I know what it is I intend to do,' she declares in Alistair Elliot's eloquent new translation. 'The rage of my heart is stronger than my reason.' The temptation to take refuge in illusion is thrillingly resisted.

As she goes off to perform the infanticides, the singing female chorus of three black-garbed peasants jabber dementedly, the gift of speaking sense jumping from one to another in turn. For chilling impact, it would be hard to improve on the staging of the final confrontation between Medea and Jason. As he batters frantically at the metal wall, two rows of the plates topple down with a crash, bobbing on cords like corpses after a hanging. Aloft, Medea is revealed, bloody-palmed, unreachable, exalting, and still full of obsessive hate, having broken Jason's heart at a visibly horrific price.

Continues until 24 October at the Almeida Theatre, London N1 (Box office: 071-354 4404).