Thais, Barbican, London

The temptation to misbehave is always greater when one is away from home. English National Opera's dalliance at the Barbican, while the Coliseum is in the final stages of renovation, has proved the perfect opportunity to do just that: something seductive, exotic, very naughty, very French. In French. How decadent is that? No surtitles - that would have been going too far. The pity is that this blissful indiscretion was a one-night stand.

Jules Massenet's Thaïs (first performed in 1894) is one of those operas that went out of fashion in order to enjoy a glorious return from exile. That's my theory. Its neglect can only be attributed to the not inconsiderable demands of its title role and the 4th-century setting, which can be pricy. Though not in the costume department, where less would definitely be more.

It's a cautionary tale of religious longing versus lust (always a promising premise for an opera), the story of Athanaël, a coenobite monk, whose mission is to save Thaïs, actress and courtesan (which operas of this period naturally assume are one and the same thing), from her divinely decadent lifestyle, and commend her to God. Though he insists that he loves her "in a spiritual way", he eventually realises (too late) that his concern for her future well-being is not, and never has been, entirely holy.

Now, any composer who can make music, real music, of that has my undying admiration. And Massenet does. It's a stonker, this score: beautiful - the mega-hit "Meditation" for violin and orchestra is by no means the headiest of its fragrances (but the only one most of us really know); exciting - a score that makes a meal of the dramatic conflict inherent in its plot, poetic reverence vying with Egyptian irreverence, piquantly scored; and full of innovation. Within minutes of the start, Athanaël dreams of Thaïs in Alexandria, and harmonium and harp usher us through a haze of orchestral incense to the sound of a murmuring chorus, from which individual voices call our heroine's name.

In the title role was Elizabeth Futral, a young American making a big name for herself. She was terrific. She'd mastered the style - the languid manner, the tremulous, sighing portamento that makes this music so enticing. She knew just how to place the role's deliciously self-regarding ascents. Her big aria, "Dis-moi que je suis belle", addressed to a mirror, is full of those. Its nerve-wracking, full-on high D did not find her wanting, though my sense was of a lyric voice pushing slightly beyond its natural boundaries.

That may have had something to do with the unabashed zeal of the conductor Emmanuel Joel, who had the ENO orchestra steaming into every Dionysian frenzy. A little over-cooked at times, and very loud; but very exciting, too. Sharing Futral's acute awareness of style was Paul Charles Clarke (Nicias), ardent and elegantly nuanced, while Richard Zeller, as Athanaël, tempered his suave baritone with some really vulnerable mezza voce.