If ever there was an opera that shouldn't work, this is it - but Phyllida Lloyd's 1999 production, revived at ENO for the first time, turns the odds around brilliantly. It's also a reminder of the fluidity and economy of Lloyd's best work.

Poulenc's 1953 score centres on an aristocratic girl who, as the Revolution brews, joins a French Carmelite order and there stumbles into a vow of martyrdom. This is a wordy piece, with genuinely moving moments embedded in navel-gazing conversations about faith and sacrifice. Without wanting to reveal too much, a bad performance can have you cheering on the hard-working guillotine in the final scene.

Yet the music is some of the composer's best, and Lloyd makes the action eminently watchable. A lack of clutter enables a constant flow; apart from two imposing movable blocks, often it's the silent characters who form the only scenery. The nuns, first seen veiled and pushing guillotine-shaped chairs through the shadows, are sinister from the start.

Felicity Palmer gives a magnificent performance as the Old Prioress, whose commanding demeanour when we first encounter her makes her vitriolic loss of faith on her deathbed even more frightening. Josephine Barstow's days of effortless vocal dominance seem over, but she has presence to spare as the unyielding Mother Marie. Blanche, the nominal heroine, is sung by Catrin Wyn-Davies, whose many-textured soprano sounds almost too complex for the character but ultimately suits her nerviness.

From reports of company strife, it might have seemed that Paul Daniel's first appearance with ENO since the end of his tenure as music director wouldn't have been a happy homecoming. But he draws a rich, occasionally over-loud performance from his players, who relish the music's heady menace.

· In rep until November 3. Box office: 0870 145 0200.