Ever since it first appeared on the stage in 2014, ‘I Believe in Unicorns’ – an hour-long show based on Michael Morpurgo’s eponymous novel has drawn much critical acclaim. The plot follows the story about a recalcitrant boy, Tomas, who dislikes books and reading, before experiencing an epiphany of sorts at his local library, where he is captivated by the stories told by its charismatic librarian – the ‘Unicorn Lady’, played with considerable aplomb by the immensely talented Danyah Miller.

Miller is an astonishingly accomplished performer and storyteller, which is just as well, given that this is a one-woman show. She establishes a warm rapport with the audience from the outset, polling the young audience members on their favourite books, which range from ‘Tiddler’ (my younger daughter’s nomination) to ‘every single book in the ‘How to Tame Your Dragon’ series’ (submitted by one little boy).

Designer Kate Bunce’s set is a bookworm’s paradise: stacks upon stacks of books, bookended by a couple of wooden ladders. Garlands of books hang from the ceiling. The room is a dilapidated library (ravaged by fire and war, we find out as the plot unfurls). The simplicity of the set belies its ability to charm: there are intricate props brimming beneath the surface, unseen until Miller reveals them with a flourish.

It is Miller, rather than the set, however, that really captivates the audience’s attention. She is utterly vibrant on stage – telling stories within stories, and frolicking round the stage with remarkable panache and zest. She involves the audience in the most disarming manner throughout the show. At one point, she invites the audience to suggest a name, place and an object, and concocts a three-minute ad-libbed story with Cindy, Cheeseland and chicken as her only prompts.

Some of Miller’s wizardry is genuinely breathtaking, and she does at times resemble an eccentric magician, plucking an umbrella out of a book here, or revealing chocolates in a book there, much to the amazement of the children (and adults) in the audience. At one point she tears out a page of book (profanity to the shocked children around me), crumples it up, and eats it. At another juncture she pours real milk from the pages of a book into a paper cone and drinks it. One scene that my daughters found particularly transfixing was when she pulled small books out of bigger books, Russian nesting doll-style, until there was nothing left other than a tiny speck of a book no larger than a fingernail. On another memorable occasion, Miller darts about the stage with a kite, pulling it from one book and then another until, finally, a huge kite swings from the rafters. There are also some beautiful projections to fire up the imagination. In one scene, Miller opens a huge book and an image of young Tomas, running and laughing, is projected across its pages.

On many occasions I found myself wondering about the fiddly logistics and technicality of it all, and how Miller keeps up the immense juggling act: there is far more complexity and depth to this show than there is in any other children’s theatrical production I’ve seen to date.

Crucial to the show’s success is the way in which Miller speaks. The artful way she modulates her tone — at times hushed, at others voluble and expansive— draws her audience in and everyone feel emotionally invested: we hang on her every word.

The key messages of the show are abundantly clear: books are precious things, and reading helps to unlock one’s imagination and generate stories and adventures. It is an intimate, spell-binding, and well-paced show, with a rich mix of humour, poignancy, and heart-warming moments. It really opens children’s eyes to the infinite possibilities contained within books, and instils a revived passion for reading in children and adults alike.

Miller’s own love of books and reading is clear, and she generously spends time in the lobby bar after the show greeting starstruck little members of the audience. She also has a comment book that she encourages children to write feedback in. The universally glowing feedback from audience members, ranging in age from as young as four, tells you everything you need to know about children’s reception to this show. The most commonly occurring word? ‘Magical’.

I Believe in Unicorns

Until 12 August at Apollo Theatre. To book, please visit theapollotheatre.co.uk