The Tempest, Royal Opera House, London

In the three years since its premiere, Thomas Adès and Meredith Oakes' haunting re-imagining of Shakespeare's The Tempest has marinated in the mind. It now has the bearing of a modern classic. With a second, or in my case, third visit, you really start to appreciate the ingenious way in which Oakes alludes to Shakespeare without necessarily quoting him. Then there is Adès' instinctive feeling for the pulse of the drama, his unerring sense of the magic that may provide the key to "a brave new world" where the sins of the parents might not be revisited on the children.

Adès is like Prospero. His score is not governed by any expectations save his own. The wonderful quintet of healing begins with a kernel of melody so pure, simple and English that it might be John Dowland. The way it burgeons into something lofty and aspirational says more about the possibilities of new beginnings than anything I know in contemporary music.

Then there is the otherworldliness of the "five fathoms deep" sounds. The passage in which Ferdinand is washed ashore has the stratospheric voice of Ariel floating on a slow and sustained orchestral wash, beautifully complemented by a visual mix of projections and stage trickery.

It is seductive and foreshadows love music in which the voices of Ferdinand (the excellent Toby Spence) and Miranda (Kate Royal - a big star in the making) assume a rapturous chromaticism. But even that cannot compare with what Adès has in store for Prospero when he realises that he cannot rule the lovers' minds. The recognition of their freedom gives rise to music of resignation tinged with a deep compassion.

With Simon Keenlyside's commanding Prospero, the mix is hectoring and gently paternal by turns; Ian Bostridge's Calibaninhabits a vocal style of baroque-like floridity. This is a contemporary opera with - surprise, surprise - arias. Only restless spirit Ariel is not grounded long enough to sustain one. He sings higher than a dog can hear. Cyndia Sieden should be paid endangerment money for her vocal pyrotechnics.

And when all humankind have deserted Prospero's island, Caliban remains, now king of all he surveys while the distant voice of Ariel can be heard finding serenity in freedom at last.

To 26 March (020-7304 4000)