SAND from Kook Ensemble is a thing of beauty. It’s at once circus, physical theatre and dance, and it charts, in as much as any art form can, the brutal rewiring of a brain that accompanies dementia.

We see a couple, very much in love, living out the regular routine of any couple’s life – morning cup of tea and cornflakes – and we see the fun they create with and for each other. Days in with the record player, and days out on the beach. A bouncy soundscape (Pete Buffery, Tayo Akinbode) evokes the energy of their younger selves (Alvaro Grande, Ebony Gumbs), full of curiosity, fun and optimism. The selves they are now (Myles McDonald, Dilly Taylor) have a comfortable ease and grace together.

When things go awry, it’s the tiny things you notice first: the teaspoon that suddenly doesn’t make sense. Creators and directors Michaela O’Connor and Sean Kempton depict cognitive decline with care and heart-wrenching compassion. Finally, in a devastating movement sequence that will linger in your mind long beyond the performance, our man starts to lose his sense of his nearest and dearest.

This is emphatically circus – we have juggling, aerial work, tumbling sequences executed with all the aplomb of modern dance – but it’s visually sumptuous circus with a brain and a heart. Adrian Linford‘s gorgeous design evokes the windswept wilds of the Devonshire coastline, just as effectively as the cosy comfort of the breakfast table. The performers make superb use of innocuous looking props to balance, to teeter, to propel themselves into the air and to somersault across the stage with apparently effortless ease. Their feather play is a piece of magic.

Sand is a consistent motif throughout the show. But the initial delightful innocence – the endless stream of sand pouring out of a magic porridge-pot style jug – erodes over the hour and five minutes, evolving into a sucker punch metaphor of a crumbling sense of self.