Britten's Henry James opera `The Turn of the Screw' was premiered in Venice in 1954. It finally made its Royal Opera debut on Thursday night, as did the production's director, Deborah Warner. So how did the ghosts of Bly take to the Barbican stage?

The kiss which Peter Quint tenderly plants on the forehead of the dying boy Miles in the closing moments of Deborah Warner's new production of Benjamin Britten's The Turn of the Screw will of course be misconstrued by those who insist upon trawling through the composer's private life in search of contemporary answers to this opera's many questions. To others, it will come as a benediction, a fond but chaste farewell to innocence, to youth, to life and love misspent. Warner has a lot - a whole lot - to answer for. Which is precisely why her production (the Royal Opera's first of this piece) is so intriguing. And compelling. And provocative by virtue of not being provocative. Ambiguous without striving to be. Scary because it's ambiguous. Like Henry James. Warner doesn't run from the uncomfortable questions that this story poses, nor does she underline or seek to answer them. She torments us with them. And that is scary.

So what are those questions, and why do they unsettle us? What exactly was the relationship between Quint and the previous governess, Miss Jessel? (Remember Michael Winner's film The Nightcomers, with its sado-masochistic overtones?) How exactly did Quint "make free" with Miles? (His words, "I'm all things strange and bold", suggest a wild one, a bit of a rebel.) Were Quint and Jessel simply the unacceptable face of permissiveness and promiscuity, robbing their young charges of their innocence, awakening in them the first stirrings of puberty? Could be. Such things were not spoken about, let alone flaunted, in the England of James's novella. Better yet, though, is the eerie tale simply a projection of the new Governess's own erotic fantasies? Is she the victim of a powerful infatuation with her employer - the children's unseen guardian? Could be.

In the scene where the Governess is first alone with her new surroundings, lolling about on the lawn, feeling, perhaps, a certain inexplicable "arousal", wishing her employer were there to see how well she was doing, the hint of rapture, the charge of excitement in her words (and the way in which Britten sets them as a fragrantly erotic pastorale) is inescapable. And it's at that moment that she first sees Quint and believes him to be the children's guardian.

It's a significant case of mistaken identity (or is it?) and Warner goes for it with intent by placing Quint at such close proximity to the Governess (not "distant", as prescribed, not some fuzzy apparition in one of the house's high towers) that he is at once tangible, real, hers. And you can smell the fear and self-loathing, the guilt. The feeling that she, not Quint, is the intruder, the interloper, gives the whole scene, the whole opera, an interesting new perspective, an extra twist, a further turn.

It's the could-bes of this staging that make it so intriguing. The world we enter, a dead, dread space, trees nestling uncomfortably in a concrete, scaffolding-clad shell (set design: Jean Kalman and Tom Pye), appears like some sort of halfway house between this world and the next. The tall, thin, louche figure (an ethereal Ian Bostridge) who silently makes his way through the darkness, from a door upstage to the incongruous grand piano downstage, belongs here. Indeed, it is as if the real "visitors" to this story are the living, not the dead, come to confront their fears, their prejudices, their desires. So the "ghosts" move freely, casually, through this environment, shadowing, "parenting" the children (whose own sense of reality is unhindered) while their protectors look on. Quint is no longer just a shadowy figure, but in the room with the Governess, vindictively knocking over a vase of flowers in order to make his presence, his displeasure, felt. He helps make up Miles's bed, for heaven's sake.

He is sung - wonderfully and with immaculate diction - by Ian Bostridge, who succeeds in making Britten's aching melismas (free and adventurous as Quint is wont to be) at once beautiful and subversive (all those near- quarter-tones). Physically, he is an adornment, draping himself around the production.

In Vivian Tierney, we have a singer and a performance almost too good, too intense, for the underwritten role of Miss Jessel; in Jane Henschel, the kindly, well-meaning but stupefyingly straight-laced Mrs Grose assumes almost Wagnerian proportions - a thrilling amplitude. Joan Rodgers is the Governess, trapped in her labyrinth, unable to keep a handle on her authority, and singing (splendidly) on the edge of an ecstasy she cannot, dare not, reveal. The children - Pippa Woodrow (10) and Edward Burrowes (12) - are terrific, Flora spinning deliciously out of control in a perpetual flurry of curtsies and cartwheels, Miles not at all "bad", just growing up too soon.

The real miracle of Britten's masterpiece, though, is in the resourcefulness, the atmosphere, the shifting subtexts of the instrumental writing. Clarity and ambiguity co-exist in his tiny orchestra. You could take away the voices, you could take away Myfanwy Piper's sometimes preposterously fanciful text, and still keep Henry James alive. With Colin Davis at the helm you certainly could.

But Warner takes us still further into this psychological labyrinth. She turns a huge, uninviting space into a small, dark recess somewhere at the back of the imagination. With a little help from lighting designer Jean Kalman, the shadows are suffocating.

Further performances: tonight, Mon, Wed, Thu and Sat 11 Oct, 7.45pm, Barbican Theatre, London EC2 (booking: 0171-304 4000). Broadcast live on BBC Radio 3 next Saturday