Down mazy corridors and dim lit archways, between the massive stone columns of New College Chapel, in a stage of scavenged props on the cold stone floor, New Chamber Opera are performing Michael Nyman’s chamber opera, a one-act numbers opera about one of the hardest topics of all; progressive dementia.

The story is familiar; Dr P, cheerful as his visual agnosia deconstructs his world, so confused by scrambled visual input he tries to put on his wife’s head instead of a hat. But the steady, progressive, hypnotic layers of Nyman’s music add new layers of complexity – and tragedy. The show opens on Sack’s friendly, professorial tones settling us in safely to observe the deficits of the neurologically compromised Timothy Colemen, he is fascinated, human, fizzing with excitement at the interesting case. Dr P, forcing good humour as his wife and the doctor fret and weave around a problem no more visible to him than the left side of his visual field, is sung by Brian McAlea in a deliciously vulnerable baritone. As he recounts his world of details and flashes the neurologist is delighted by the workarounds, the body music, his inner soundtrack. His wife, expressed by Rose Rand’s impassioned soprano, is devastated.

As consultation progresses and coping mechanisms dissolve under examination, Dr S’s delight in the magnificent efforts of Dr P’s broken brain is shredded by her clear, undeniable humanity. The dim space shudders under layers of symptoms described and disguised, concealed and revealed, while Dr P sits surrounded by the progression of his illness, increasingly alone, happy music playing in his head. Under the shimmering gracetones of the final prognosis, sad smiles flick between the players; nothing can be done. So they drop a bow, like string-cut marionettes in worn shoes and crumpled suits, and the lights go out.