As we see all too often, an opera director can easily fall into the trap of over-thinking a new production and that is what seems to have happened in Fidelio at the Royal Opera House. Beethoven's only opera poses a big problem to any director: the second act has a markedly different character from the first and Tobias Kratzer's way of dealing with this only emphasizes the problems.

The story is set around the time of the French Revolution and features the incarceration of Florestan, a political prisoner held in a harsh jail where he is being starved to death. His wife Leonore disguises herself as a man called Fidelio to infiltrate the jail in an attempt to find him and free him. The first act is thus a gripping story of intrigue and love, with more romance and a little comedy introduced by the head jailer's daughter Marzelline falling in love with Fidelio, unaware that he is a woman.

The leading parts in this are played brilliantly. Irish soprano Jennifer Davis is superb as Fidelio with a glorious voice, especially her soaring high notes, and convincing acting skill. At the start, she is fully matched by Austrian soprano Christina Gansch as Marzelline but as Fidelio's role grows, Davis dominates the stage. With Marzelline's father the prison warden Rocco also played excellently by English bass Peter Rose, the magnificence of Beethoven's music is gloriously displayed when these three are singing. With the Orchestra of the Royal Opera House on superb form under British conductor Alexander Soddy, and the chorus impeccable in their unity, the first act was a real treat.

The second act was very different and was meant to be, but surely not as different as Kratzer made it. At the start, we finally meet Florestan, incarcerated alone in a dank, dark, deep dungeon of the prison and chained to a rock, but this dungeon is brightly lit and his misery is being observed by an audience, seated on chairs around the rock.

I suppose that the idea comes from the contrast between the two acts: the dramatic intrigue of the characters gives way to a more philosophical treatment of the indifferent reaction of the populace who allowed this to happen. Yet we already have an audience in the opera house watching it all and nothing is gained by having an onstage audience as well. This is all rather a shame as the American tenor Eric Cutler plays the part of Floristan with a fine voice and great dignity, while German baritone Jochen Schmeckenbecher seethes and rants chillingly as his bitter enemy, prison governor Don Pizarro.

Beethoven's music is brilliantly crafted, and superbly displayed by the numerous duets, trios and quartets sung by the fine cast, but the second act rather lets them down.

Fidelio is playing at the Royal Opera House until 16 October.

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