The Royal Opera's Fidelio is an import from the New York Metropolitan Opera, where it was first seen in 2000. Directed by Jürgen Flimm, it caused a stir at the time, largely thanks to a tremendous central performance from Karita Mattila as Leonore. Seven years on, UK audiences now have the chance to discover what the fuss was about, though whether it works in its totality - or ideally serves Beethoven - is debatable.

Flimm relocates the opera to an unspecified South American dictatorship in the second half of the 20th century. He's exceptionally strong in his examination of the impact of brutality on people's lives. The prison doubles as an arsenal, where we find Marzelline (Ailish Tynan) and Jacquino (Robert Murray) going through a daily routine of cleaning guns and packing them in crates. Florestan (Endrik Wottrich) is held in a vault that also contains the battered suitcases of those who have disappeared before him. Pizarro (Terje Stensvold) is a thug, Rocco (Eric Halfvarson) an opportunistic turncoat. Mattila, meanwhile, plays Leonore as a woman forced to exploit this dire system in order to subvert it. She's fretful over her male disguise and riddled with guilt at having to pretend to fancy Marzelline. Nobility of purpose is balanced by the rage and doubt that periodically course through her voice. At the end, when her nightmare is over, she is ecstatic, flooding the auditorium with waves of sound.

There are lapses and inconsistencies. Prior to the Prisoners' Chorus, Mattila unlocks their cells without authority to do so - a departure from Beethoven - which sits uneasily with her pretences of conformity. There is so much gunplay throughout that the scene where she turns a revolver on Pizarro is anticlimatic. Most of the religious subtext has been jettisoned, and we lose sight of Beethoven's questions about the presence of evil in a divinely appointed universe. Musically, the evening also operates on several levels of inspiration. Only Wottrich equals Mattila in fire and commitment. Halfvarson hasn't the vocal subtlety to match his dramatic interpretation and Stensvold, though impressive, can be monochromatic. Conductor Antonio Pappano took an age to settle, only achieving intensity of expression in the second act, after a start marred by moments of poor co-ordination between pit and stage.

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