Operatic characters frequently lose their reason, notably in the works of the bel canto era. It’s usually a tuneful matter with the audience afforded the further comfort of knowing either that it will all come right in the end or that the delusion acts as a cushion against fatal violence. Elena Langer and her librettist Glyn Maxwell put an altogether darker scenario before us in The Lion’s Face.

We are in a care home, bleak and clinical in its white cleanliness (an effectively simple set by Alex Lowde. Snow is falling outside the window. A man whose age hovers between middle and old stares out. This is Mr D, who suffers from dementia in the shape of Alzheimer’s disease. His is a spoken role, setting him apart from his wife, the doctor, the care-worker and her daughter – the other contemporary people whom we meet – all of whom are singers. Mr D lives in a receded past; it’s one which excludes those whose lives are affected by his condition.

This is music theatre in its truest sense. The 12-strong instrumental ensemble under Nicholas Collon is behind a translucent screen at the back of the stage. Langer’s score wraps around the situations as they unfold with tonal certainty and with rhythm as well as melody breaking through for the daughter and the pre-recorded and filmed children of Mr D’s skewed recollections. The music flows between the singers’ direct use of it and the instrumental commentary on what is happening. The dialogue is naturalistic, requiring good articulation from all concerned.

As Mr D Dave Hill gives a moving performance, attentive to the music – whether played or sung – which accompanies his verbal ramblings but never falling into the trap of vocalising them. Rachel Hynes is also good as the care-worker whose attention to her patient seems to take precedence over her concern for her young daughter.

Mrs D is sung by Elizabeth Sikora, coping with some difficult vocal passages at the expense of clear enunciation; she is as much a victim of the disease as her husband and should command equal sympathy. Ffur Wyn is thoroughly credible as the daughter, projecting teenage angst and ripples of high notes with equal aplomb. Benedict Nelson is good as the doctor whose concern for his patient is fused with a desire to make a clinical break-through.