Jakob Lenz, Hampstead Theatre, London

After winning both of the opera awards at the Oliviers last weekend, and savouring the presentation at the Royal Opera House, home of its only serious rival, English National Opera is riding high. As if to underline the commitment to adventurous programming for which it was singled out, it now has its sights on two works by living German composers, and the first of these, Wolfgang Rihm’s Jakob Lenz, was unveiled on Tuesday. Rihm’s 1978 chamber opera, a dramatisation of the crumbling state of mind of the 18th-century poet, is not new to London – the Almeida Festival staged it in 1987 – but the decision to offer it to a new generation of opera-goers, in an attractive venue new to opera, was understandable. It shows how fertile Rihm was at the age of 25 – he is now 60 and one of German culture’s elder statesmen – and its chamber proportions were hardly going to expose ENO to excessive risk.

Full marks for initiative, then, but the venture is not a success. Jakob Lenz comes across as representative of a type of German music theatre that may have seemed important 25 years ago but now comes across as exhaustingly dense. The opera claims for Büchner’s simple narrative a depth and seriousness that its highly strung music and one-dimensional dramaturgy cannot sustain. There is only one “real” character, the delusional Lenz, beyond whose skewed vision of reality the piece never breaks out.

Sam Brown’s production, designed by Annemarie Woods, is more a hindrance than a help. It unfolds in a swamp (the swamp of Lenz’s mind?), cluttering a narrow stage space. The cast splash around in ankle-deep water, and some scenes involve full immersion. Brown introduces characters to which the libretto makes only oblique reference. All this detracts from the starkness of the material.

It does not detract from the evening’s centrepiece – a typically courageous performance by Andrew Shore. His identification with Lenz is so powerful that he really belongs in a different show. ENO’s chamber ensemble, conducted by Alex Ingram, resists the temptation to soften Rihm’s often strident sound-world, but the task seems thankless.

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