Lucy Grace was 26 when she had an epiphany on the edge of Brockwell Lido and realised that Narnia doesn't exist. From the age of ten she had believed that not only was she connected to The Lion, The Witch and the Wardrobe's central character Lucy Pevensie by virtue of name-sharing, but that she was one day destined to head through a portal and discover CS Lewis' fantasy land.

Her revelation, and its knock-on existential crisis, led her to a new quest to fill the imaginative void vacated by Narnia. The resulting show tracks her progress as she goes in search instead of the real Lucy Barfield, to whom Lewis dedicated his book.

Lucy Barfield, however, is something of a mystery, one which deepens and twists the more Grace learns about her life. At heart, this quiet, velvet-gloved punch of a piece unfolds into a meditation on the nature of fantasy versus reality and the power of imaginary landscapes to broaden, enrich and become part of our lived existence. Grace's delivery brims with effusive energy, and despite the gut-wrenching curveballs her journey throws at her, there is a bittersweet triumph in finally honouring one of children's fiction's most treasured muses.

Pleasance Courtyard, until 29 Aug (not 15, 22), 3.30pm, £9-£10 (£8-£9).