Un Ballo In Maschera, Royal Opera House, London

Ridiculous and then sublime

Verdi's original title for Un Ballo in Maschera was Gustavo III, after the Swedish monarch assassinated during one of his own masked balls in Stockholm in 1792. But the Italian censors moved in after an attempt on the life of Napoleon III in 1858 and, much to the fury of Verdi's adoring public, demanded changes.

Verdi's original title for Un Ballo in Maschera was Gustavo III, after the Swedish monarch assassinated during one of his own masked balls in Stockholm in 1792. But the Italian censors moved in after an attempt on the life of Napoleon III in 1858 and, much to the fury of Verdi's adoring public, demanded changes.

The setting was shifted to Boston - as far away from Europe as possible - and, as they say in true-life crime dramas, the characters' names were changed to protect the innocent. As a result, none of it made much sense at all. Only the title bore testament to Verdi's original inspiration.

What a surprise, then, to be back in Boston for Mario Martone's lavish staging at the Royal Opera. Why? So that the sinister Ulrica, who foretells our hero's death, can once more be branded "a vile woman of negro blood"? Or, more tenuously, because, according to the programme note, Martone thinks that "the waltz" in act three, scene two, is suggestive of the America of Verdi's time, an "America being born with the same sort of unbounded energy we find in the character of Riccardo". Firstly, it's not a waltz, secondly it may not actually matter where the opera is set but it does matter that the character of Riccardo or Gustavus III or whatever you want to call him is portrayed as Verdi conceived him - a flamboyant luvvie with a penchant for pageboys and parties.

We get the party alright: Martone's masked ball arrives like a vertiginous aerial shot (well he is a film director) cleverly framed in a huge tilting mirror. That same mirror reflects the auditorium, putting Riccardo well and truly "on stage" for his key aria at the start of this act. But so little has been established with regard to his "theatricality" (the real Gustavus was, by all accounts, a bit of a drama queen, as liberal as he was sexually ambivalent) that the moment makes little or no sense.

Actually, this is a production of two distinct halves. The first is creakily and ineptly nondescript, the second is strikingly but all too suddenly and belatedly alert to the dramatic potential. Huge, disruptive intervals frame the crucial central act in the shadow of the gibbet. It has a spectacular set, to be sure (designed by Sergio Tramonti), but what an irony it is that so much rubble takes so much time to assemble. I wouldn't mind, but this scene hasn't been so dramatically stilted since Pavarotti decided to leave the stage for a glass of water in the last staging here. It is a desperate director who has one of the conspirators symbolically hang Amelia's veil on the gibbet.

But into this dubious piece of theatrical nonsense step three of the best singers in the world.

Marcelo Alvarez gets to feast on one of Verdi's most substantial tenor roles, and does so with a musicality and finesse that contradict his physical stiffness.

The part of his friend and rival Renato allows Thomas Hampson a more dramatic outing than we generally associate with him. I'm still not convinced that his lovely voice naturally lends itself to the required weight and incisiveness (and the part does lie a little low for Hampson) but he certainly rises well to the fury and hurt of his third-act encounter with Amelia. His motivation for "Eri tu" is no doubt redoubled by the presence of the fabulous Karita Mattila. What makes this singer so special is not just the shining amplitude of the sound or her ability to taper those eternal Verdi phrases so they quite literally float on the breath, it's the fact that every note she sings seems to be sourced from deep inside her.

The dramatic and vocal and emotional high point of the evening was her aria "Morro, ma prima in grazia", where she pleads to see her son again. The intensity of that is almost unbearable. We had travelled a lot further than Boston from the ham and vocal pneumatics of Elisabetta Fiorillo's ludicrous Ulrica in act one. It was that sort of evening.

To 30 April (020-7304 4000)