Opera: Cherubini's Medea; Grand Theatre, Leeds

It's a story from your daily paper: marriage crumbles, husband abducts children, distraught wife resolves to get them back by any means necessary. For all its classical trappings, Cherubini's Medea is heart- stoppingly veristic. As long, that is, as the singer in the title role has the power to make it so.

A reviewer of the 1797 Paris premiere reported that Mme Scio, the first Medea, "tore out our souls". So it is with Josephine Barstow in Phyllida Lloyd's new Opera North staging, which opened on Monday. Barstow is remarkable, so much so that she sometimes seems to be in a different opera from the rest of the cast. Or is it that Medea, granddaughter of the sun god, inhabits a world separate from the mere mortals around her?

Kandis Cook's costumes place the action in the court of some 18th-century nobleman, rendered a touch exotic by the vaguely Eastern headgear worn by Norman Bailey's Creon and Thomas Randle's Jason. Here, everything is order and grace. About to become Jason's second wife, Nicola Sharkey's Dirce opens the opera with a bout of pre-nuptial nerves; her retinue calms her with a display of synchronised sewing. Marriage goes ahead, joy is unconfined.

Enter Medea. Dressed in sumptuous black rags, the sorceress prowls menacingly around the unseeing newlyweds, seemingly able to stop time in its tracks. But when Barstow sings, Medea becomes mortal, racked with all too human agony. Her voice, never the most sheerly lustrous, cuts through bel canto convention to find beauty in pain. Sometimes it sounds strangulated, the chest register is fierce and frightening, but this is acting through the voice, and it makes for uncomfortable drama. Since this is opera-comique (in Kenneth McLeish's lucid translation), there is plenty of spoken dialogue, and Barstow acts it where some of her colleagues merely deliver it.

As Medea's servant Neris, Anne Wilkens comes closest to matching her, and sings her Act 2 aria beautifully. Randle's Jason has moments of vocal dignity without always defining Cherubini's line clearly; and if there is no longer a lot of colour in Bailey's voice, he has the weight for Creon. Sharkey's Dirce looks frail, but has the pinpoint accuracy familiar from her many Queens of the Night. A pity she doesn't have more to do.

Ian MacNeil's set is a wooden spiral staircase, with a perspex cylinder at its centre. There are some telling moments on the stairs, as when Dirce slithers headlong to her death, but too often Lloyd simply marches singers up to the top, then marches them down again. In general, she wisely clears the stage to make room for Medea, supported superbly by the English Northern Philharmonia under Paul Daniel. At first the overture sounded thin, small-scale, but Daniel quickly got the measure of Cherubini's elegantly stirring phrases, seething beneath an apparently unruffled surface. That's what makes Medea such a thrilling opera.

n In rep to 26 April at Leeds Grand (0113 245 9351)