A new Peter Brook play is always keenly awaited. This one, which the 89-year-old director has co-written and co-directed with his long-time collaborator Marie-Helene Estienne, is the latest in a series of plays on neurology. It explores synaesthesia - enhanced responses to the world's stimuli.

In some people, it results in an incredible ability to retain facts and sequences of numbers. In others, colours and tastes are triggered by words. None of this is easy to evoke. Brook regulars Kathryn Hunter, Marcello Magni and Jared McNeill play either those who have the condition or doctors who are researching it. The short and wistful play does give a sense of what a synaesthetic feels. But, of course, what you want is to understand the actual experience rather than than the emotions it triggers. On this, the show does its gentle best but ultimately leaves you less than astonished.