The Light Princess

Adapted from a Victorian fairy tale, with a score by Tori Amos and a libretto (and lyrics) by Samuel Adamson, The Light Princess is a delightful and unusual surprise at the National Theatre, a grown-up musical pantomime about a royal girl, the Princess Althea, whose grief at losing her mother makes her float above the earth until she becomes a creature of the lake and is rescued by a neighbouring prince.

Wicked fans will love the fact that Rosalie Craig – giving one of the most extraordinary, vocally resourceful and physically triumphant performances I have ever seen in musical theatre – is literally "defying gravity" for well over two-and-a-half hours.

She swoops, she soars, she fights, flies and flickers like a candle in the wind, a cascade of bright ginger Pre-Raphaelite hair streaming out behind her as she sets an all-time Lyttelton record for the occupation of cubic space, supported on invisible wires and by three black-clad, moustachioed acrobats, impassive witnesses to her predicament.

At one point, after she's fallen to earth at last, thanks to Nick Hendrix's charming Prince Digby – overcoming his own handicap of unwonted solemnity – she lies horizontally in mid-air, apparently levitating, suspended on her acrobats' up-thrusting feet.

Marianne Elliott's production – which opens in front of a vividly coloured pantomime cloth by designer Rae Smith indicating the rival kingdoms separated by an emerald wilderness and the fateful lake – is full of such fluid, inventive physicality, mixing it with cartoon comic strip, puppetry and projections; all courtesy of the War Horse team of Paule Constable (lights), Steven Hoggett (dance), Toby Olié (puppets) and musical director Martin Lowe in the pit.

Narrative clarity is not the show's strongest suit, a lot of the courtly huff and puff going for nought – in the George MacDonald original, Althea is cursed by a wicked witch, simples – but you soon learn to submit to the slow-motion antics of the excellent ensemble (that extraordinary beanpole and quondam Qdos panto major-domo David Langham prominent among them), and the wash of Kate Bush-like exclamatory music that is never predictable and always interesting, laced with complaint, melody and a modern sort of operatic hysteria.

Apart from the technical virtuosity in Craig's singing, there's a remarkable bolted-together double number for Clive Rowe as her angry father that fully exploits his lyrical range (and octave reach!), and a wonderful aquatic number for Althea, Digby and a bobbing lake-full of sea anemones, bulgy-eyed frogs and flying fish. Stand by, too, for a wintry wonderland of a happy ending with a frosted pink constellated landscape that has already upstaged Selfridges' and Fortnum's Christmas shop windows before they're unveiled.

So, is this the new War Horse, then? Despite the panto elements, it's a much tougher show and in many ways more daring, not least because of the music and Adamson's lyrics (this is his second great musical theatre adventure of the year, following the glorious Gabriel at the Globe); it must be a nightmare to run in repertory, so the sooner it's moved into the West End, probably the better.

And I hope the whole of Elliott's fine cast stay with it as they tidy up the loose ends, which they must. Amy Booth-Steel is an eye-catching Dandini figure and Laura Pitt-Pulford equally watchable as her more sinister opposite number on the prince's side. Tori Amos has helped out on her own orchestrations (with John Philip Shenale) and vocal arrangements, and the superb aerial effects are designed by Paul Rubin.