Pelleas Et Melisande, Royal Opera House, London

The long, slow, beautiful but elusive exposition of Debussy's Pelléas et Mélisande is a huge challenge to bring off in the theatre. The director Stanislav Nordey didn't even come close. Better, on this occasion, to close one's eyes and let Simon Rattle and the magnificent Royal Opera Orchestra open magic casements to the ineffably sad soul of this masterpiece.

Except, of course, that mine were wide open, trying to ascertain what exactly was going wrong. The problem seemed to lie with Nordey's reliance on his designers and his failure to integrate his work with theirs. There were times during the interminable opening acts when there seemed to be two shows going on: one a kind of Turner Prize exhibit; the other (in terms of blocking) a rather routine touring-opera production. It was only in that extraordinary scene where Golaud, in his agony and impotence, uses his son Yniold (the remarkable George Longworth) to spy on Pelléas and Mélisande that everybody seemed to get a grip.

It's hard to fail with that scene, but even there, Nordey almost defused the mounting tension, the unbearable threat of parental abuse, by physically separating father and son at the heart of it. How chilling, though, for us to see, for once, what the boy is seeing. The set designer Emmanuel Clolus offers a gravity-defying image of Pelléas and Mélisande floated, as it were, halfway up a white wall, just simply sitting, some distance apart, and gazing into each other's eyes. The contrast between the chastity of that image and the ravages of Golaud's jealousy could hardly be greater. So, at least one dramatic point scored.

Up until that moment, however, the stage narrative was entirely driven by Clolus opening up a series of huge "Chinese boxes" and illuminating something emblematic to the scene in question: a wall of Pelléas's letters to Golaud in one; Mélisande's white flowers in another; the lovers' names spelled out in Braille to underline Arkel's failing sight; bloodstained pillows pertaining to Golaud's hunting accident; and, inevitably, Mélisande in the tower, like a butterfly in a display case, countless replicas of her red dress arrayed on either side.

A variation of that image re-occurs at the close of the piece, with a nightmarish image of Raoul Fernandez's generic costuming of all the inhabitants of Allemonde - a hideously unflattering pantaloon suit, Star Trek meets Cirque du Soleil.

But this was a Pelléas et Mélisande that was too much about appearances and too little about soul. I did not for a moment believe in Angelika Kirchschlager as a creature who "could give God lessons in innocence". Lovely singer, but neither vulnerable nor touching enough, and too much of this world. Simon Keenlyside was another matter, singing beautifully, ardently, magnificently in the sublimation of his final meeting with Mélisande. Finley was splendid, too, but for me there was too little distinction, physically and vocally, between him and his half-brother Pelléas.

Robert Lloyd exuded wisdom and gravitas and compassion as Arkel, the King of Allemonde. Of all the characters in the piece, it is he who finally unlocks the humanity in Debussy's enigmatic score. Rattle, whose wonderfully transparent realisation was a constant source of intrigue, dug deep into Arkel's despair, his orchestra welling up unforgettably with the line, "If I were God, I would take pity on the hearts of men." If only.