MUSICAL / Well, did you heifer: Robert Hanks on The Challenge at the Shaw Theatre

You would guess that the most difficult challenge facing the creators of The Challenge was to find a tasteful, dramatically convincing way of portraying the romantic liaison between Pasiphae, Queen of Crete, and a bull. In fact, refusing to be cowed, they simply steered clear of the difficulties, and opted for a neat solution: bury the whole event in cattle jokes - 'a bit of the udder', 'cock and bull', a song based on permutations of the word 'Lovable' (love a bull, lover-bull), and a hilariously unpleasant number by Anthony Drewe and George Stiles, 'Bull Inside My China-Shop', including the couplet 'I want to have a bull, and yet I wonder, will it ache? / I've never had my larder chockablock with fillet steak.'

So, no beefs about that aspect of the show: and the first half of Sunday night's one-off showcase performance of The Challenge succeeded brilliantly. From Howard Goodall's scene-setter, 'The Mediterranean Sea', the performances and the staging had a professionalism and a verve matching anything in the West End. Stephen Clark's book, too, showed narrative ingenuity, tying together the disparate strands of the Greek myth of Daedalus, 'father of inventors', and providing a surprisingly coherent framework for the disparate efforts of the 28 composers and lyricists of the Mercury Workshop who wrote the songs.

There are weak moments: Daedalus' status as master technician of the ancient world inspires a couple of sub-Kipling hymns to craftsmanship - 'From Nothing to Something' and 'Working with Wood' ('Nothing's as good / As working with wood'). And towards the end of the first half, after a lot of dallying over Pasiphae's calf-love (satisfied by means of a hollow wooden cow built by Daedalus), the plot becomes very crowded. In rapid succession, Pasiphae gives birth to the Minotaur; her husband, Minos, makes Daedalus build the labyrinth, and shuts him, his son Icarus, Pasiphae and Minotaur in it; Pasiphae eats herself to death; and the Minotaur discovers a taste for human flesh.

The two numbers that cover most of this - 'Garden of Dead Ends' by Edward Hardy, and Charles Hart's 'Home; Food; Blood' - are by some way the most ambitious numbers of the show, in their density of incident and emotion. But, after the lightness of everything that's gone before, they seem rather confused: Pasiphae isn't the only one who has to cram an awful lot in.

In the second half, things go badly wrong, partly because all the real show-stoppers have been used up before the interval. But the plot loses impetus, with Theseus' slaying of the Minotaur reduced to a distracting interlude, and rich, mythic themes seem to have been replaced by cliches. 'Am I Alone' makes Theseus a dreamer, laughed at by his companions, with Ariadne the woman who believes in him; while in the closing number, 'If I Tell You', Daedalus - now lamenting the death of Icarus - realises that things would be fine if we just learned to express our feelings. Still, this disappointment is a small price to pay for some clever, funny and slick song and dance. Everyone involved should be feeling ebullient.