The Lion's Face, Opera Group

An opera about Alzheimer’s disease might seem an idea calculated to send the most community-minded audience rapidly to the nearest exit. Yet there's a longish history of theatre – musical and otherwise – about loss of memory and the failure of language, from Wagner to Bartók to Beckett to (even) Michael Nyman; and if Elena Langer's new piece for The Opera Group, The Lion's Face, ultimately fails to measure up dramatically to that tradition, it may be because, in approaching the subject from a clinical angle, it imprisons itself in the inescapability of the condition itself, without hope of change or catharsis.

Glyn Maxwell's libretto deposits us unceremoniously in a modern care home – white PVC chairs and plate glass windows – and leaves us there for the duration. Mr D, an advanced sufferer, is trying vainly to assemble his thoughts and memories, while his wife, his carer and his doctor try no less vainly to find some route into his fragmented consciousness. Only the carer's schoolgirl daughter – a coloratura role brilliantly dispatched here by Fflur Wyn – manages to break through by the, one might think fairly obvious, recourse of humouring his misconceptions instead of (like everyone else) contradicting them.

Langer and Maxwell spent some time researching Alzheimer's and dementia with the help of a learned professor and assorted psychologists, therapists and social workers, and we can take it that their observations are authentic. Alas authenticity guarantees nothing in the theatre. Maxwell surrounds Mr D, a spoken role, with what amounts to a group of stereotypes who make no significant emotional contact with him. His wife, so far from loving him, seems at best puzzled, at worst exasperated by his unseeing mind; the carer treats him like a three-year-old ("Here comes the special breakfast ride and down we go"); the doctor regards him as a case. The relationships are not developed, and the libretto misses the opportunity to evolve a magical response to the confused images that well up in Mr D's memory.

However, what might have been a fairly morose Sunday evening in Oxford's Playhouse Theatre (following Thursday's premiere in Brighton) is rescued by the exquisite detailing of Langer's score, by John Fulljames's neat, well-observed production, and by a uniformly excellent cast of singers and players. Langer's music may not be inherently dramatic, but it is constantly arresting in sound and melody, individual in cast, precise in execution. A Moscow-trained Russian, she has worked her way through a powerful Stravinsky influence, notably in a dazzling set of folk-derived songs (Songs at the Well) indebted, but by no means subservient, to Stravinsky's Pribaoutki.

In The Lion's Face (a title taken from John Bayley's description of Iris Murdoch) she writes for voice and a 12-piece chamber orchestra with no less flair, evoking the tangled polyphony of Mr D's brain with cascades of high woodwind and percussion, but then unexpectedly leaving him alone with a solo cello, marvellously sorrowful and sympathetic. She can also write good tunes of modest banality for limited creatures like the carer, who tends to break into waltz time but also has a catchy duple-time song about a birthday present (reprised in Act Two, Jerome Kern fashion, by Mrs D). This is an integrated, attractive score that one wants to hear again. I only wish it were attached to a more gripping dramaturgy.

Fulljames and his designer Alex Lowde, nevertheless, make the most of what is here, with discreet but effective use of back projection by Ian Galloway (for the patient's clouded memories) and a vivid line in falling snow which, for some perhaps deep psychological reason, suddenly falls upwards at the start of Act 2.  Dave Hill, as Mr.D, is a frighteningly convincing portrait, as difficult – I imagine – as Beckett at his most convoluted, and there are fine supporting performances from Elizabeth Sikora as the wife, Rachel Hynes as the so-called Caregiver, and Benedict Nelson as the (also so-called) Clinician-Scientist. Nicholas Collon conducts with fine energy and control, and the playing seems nearly flawless.

• Further performances of The Lion's Face in Newcastle, Watford, Cardiff and Cheltenham and the Royal Opera House