THEATRE / When violence masquerades as love: Paul Taylor on Le Cid, Corneille's tale of conflicting honour and desire, at the National's Cottesloe Theatre in London

Falstaff famously belittled the idea of honour: 'What is honour? A word. What is in that word honour? What is that honour? Air. A trim reckoning] Who hath it? He that died a' Wednesday. Does he feel it? No. Does he hear it? No.' - considerations that prompt the fat knight to end his mock catechism by saying he'll therefore have none of it. When you've sat through two hours of Pierre Corneille's Le Cid, Falstaff's cynical, easy-going attitude may begin to strike you as a wonderfully refreshing alternative to the sort of tortured, unrelaxing extremism on display there. Taking place in Seville, at the court of the King of Castile, the play shows you a society where both sexes are trapped in a rigid male code of honour and torn apart as their ideals battle with their desires.

Ximena (Susan Lynch) and Don Rodrigo (Duncan Bell) are about to be betrothed, but their happiness swiftly turns to agony when the Count, her puffed-up military-hero father (Edward de Souza), insults the elderly father of Rodrigo (Alan MacNaughtan), the hero he superseded.

The code demands that insults be repaid at all costs, with the result that Rodrigo, riven between his desire for vengeance and his passion for Ximena, slays the Count and lands her in the equally fraught and invidious position of having to call for retribution against him.

The set for Jonathan Kent's arresting Cottesloe production is dominated by two huge gilt looking-glass frames slumped forward on an undignified tilt. The one is empty, the other a magic mirror capable of flashing up images from the mind's eye, or of counterpointing one character with another on either side of the looking-glass divide. At the start, for example, as Ximena is being laced into her clothes by her servant, we see the same activity mirrored behind her in the dressing of the Infanta (Samantha Bond). It's a stage picture that eerily conveys Ximena's unwitting surrogacy, for it turns out that the Infanta has calculatingly fostered the girl's ardour for Rodrigo, or, as she puts it in the impassioned balance of Ranjit Bolt's eloquent translation 'Lit fires in her to fight the fires in me'.

Positively shaking with the strain of ill-suppressed desire and having to clutch at pillars for support, Bond's stiff, tottering Infanta offers a terrifying authentic study in fixation. Knowing that Rodrigo is too low in rank for her, she has endeavoured to put thoughts of him aside by marrying him off: 'I dare not hope until all hope is gone.' But then events conspire to give her hopes sickly resuscitation. When Rodrigo wins renown for saving Castile from the invading Moors, she questions whether the class difference now matters . . .

Their obstinacies over honour tying them into ever more elaborate knots, Ximena and Rodrigo could easily turn into a comic pair in front of an English audience, so it's a tribute to the slightly crazed integrity of Duncan Bell's Rodrigo and the blazing-eyed, bawling vehemence of Susan Lynch's raven-haired, determined slip of a Ximena that they manage to ward off irreverent laughter until the last act.

Partly, the problem there is that while the feeling of the play is tragic, the plot swerves towards a tragicomic conclusion. Tricked twice into a volubly unguarded display of emotion on the mistaken assumption that Rodrigo is dead, Ximena cannot be said to conclude the play with dignity undented. You feel, by this stage, that she's done enough to deserve the suicide option. Indeed, for all the intellectually absurd postures the code of honour has forced on them, there's a sense in which the play betrays the central couple's uncompromising intensity in delivering them up to a 'happy' ending, even when it's as muted as the 1682 version used here.

'El Cid' is in repertory at the National Theatre, London SE1 (Box-office: 071-928 2252)