Preview: Gotterdammerung, Royal Opera House, London

'This is the music I was born to sing'

When Lisa Gasteen first sang Brünnhilde, she said that she felt so comfortable she might have been playing herself. "That was then, but I'm not so sure now." Will she elaborate? "I'm having problems with particular notes, and because I'm a very physical person, and like to move a lot, and am extremely strong," - her handshake is pulverising - "I tend to make things more difficult for myself by all kinds of violence. That interferes with the vocal side."

As the gods don't mess with Brünnhilde, so you don't mess with this powerfully built Australian, who'll be hurling herself around in the final leg of Keith Warner's Covent Garden Ring on Monday. The production, she says, has grown organically, and makes Wagner's mythology vividly relevant today.

What's the message of this particular show? "It's about family dynamics, and politics - Hagen operating behind the scenes to bring about people's downfall, for his own gain. We keep making the same mistakes in history. We know what brings peace, but we let vested interests carry on waging war. Yes, of course I'm talking about Iraq. But we don't talk like this in rehearsal. We'd go mental if we did."

She's more explicit about her own character. "Brünnhilde is all about disintegration, from goddess to someone fully human, in the ugliest possible way, when she finds herself betrayed by everybody, and turns nasty, full of anger and lust for revenge. But she finally learns acceptance, and by the end, when everything around her is dead and shattered, what remains is hope."

That hope is expressed in an extraordinary 15-minute solo, which, for Gasteen, is transfiguring. "The power of the music just fills me, makes me feel I'm bigger than I am. It expands me - ha-ha! - size 24, coming up!" Will she ever sing any other repertoire, now that she's so firmly typecast? A sad shake of the head. "I doubt it. But this is the music I was born to sing."

From 17 April (020-7304 4000; info.royaloperahouse.org)