The Midnight Court Opera is a new vision of music theatre from Canadian company Queen of Puddings. It's a tale of fairies, frolics and sexual politics, based on an 18th-century Irish poem by Brian Merriman in which a nocturnal court, presided over by the Queen of the Fairies, decides on the fate of the nation's unmarried women: why are there so many single men in Ireland, and why is nobody marrying the country's women? With its plea for sexual liberation, the poem was a radical critique of the repressive Catholic church in the 18th century. In the 21st, the moral of the story seems quaint and anachronistic.

However, director Michael Cavanagh and conductor Dairine Ni Mheadra think The Midnight Court still has the power to shock audiences. But their staging, with a score by Ana Sokolovic and libretto adapted by Paul Bentley, has all the drama of a second-rate panto. Alexander Dobson's Poet settles down to sleep in a forest only to be awakened by the fairies - dressed like extras from an Adam Ant video - led by Krisztina Szabo's Queen. A quartet of harpies are her magical minions, evoking spirits as she creates a battle of the sexes in fairyland. Shannon Mercer's Grace is a petulant, infantile 18th-century Bridget Jones, complaining that despite her charms, she can find no one to marry. John Kriter's odious Snarlygob puts the men's side of the story, and finally the fairies decide that the Poet himself is guilty, as a single thirtysomething with no interest in marriage. He is whipped and chastened, and wakes to the possibility of finding love.

It's a thin story, and neither Michael Gianfrancesco's designs nor Sokolovic's gestural, histrionic music can save it. For all the efficiency of the singing, the piece is never more than a superficial romp in fairyland. It's not racy enough to be interesting as theatre, nor experimental enough to be engaging as music.

· Ends today. Box office: 020-7304 4000.