Maurice Maeterlinck, who wrote the play on which Debussy's Pelléas et Mélisande is based, frequently compared the world to a hospital and mankind to its patients. His bleak metaphor dominates Jossi Wieler's and Sergio Morabito's Hanover State Opera production. It proves to be an intransigent piece of music theatre that obfuscates the work's intentions.

Debussy's contention is that we are all essentially mysterious creatures, unknowable to our fellow human beings. The opera's force derives from the fact that we, like Golaud, remain unclear both as to whether the relationship between Pelléas and Mélisande is actually sexual, and also as to which of the two men is the father of Mélisande's child. In transposing the work to what appears to be the psychiatric ward of a modern hospital, Wieler and Morabito have jettisoned its central mystery, replacing it with other riddles that obscure the narrative even further.

Arkel and Geneviève flap about like a pair of benevolent new age gurus and may be psychiatrists - although they're prone to smoking dope and could also be druggies. Yniold is hyperactive and throws continuous tantrums, while Pelléas is infantilised and mother-fixated. He and Mélisande are, fatally, never left alone until the Act Four love duet, at the end of which Pelléas is gunned down by Golaud, played as a sadistic psychopath, who virtually assaults Mélisande in the opening scene and may have a paedophiliac interest in Yniold.

Golaud should be the opera's tragic centre, but by morally placing him beyond the compassion urged by Debussy's score, Wieler and Morabito have undermined the whole work. Musically, much of it is impressive, but the production fails to do Debussy justice.