There are two sources of drama in this sly and fascinating show, which goes by the title DoorWays. Most immediately striking is the set: two steel-door frames and an unglazed metal window, whose apparently immutable lines turn out to be as versatile and surprising as the human element. A door, which we assume to be fixed, suddenly starts to behave like a giant swingboat; another folds in on itself to make prison bars; two frames merge before our eyes to make an outsized Velux skylight, its mobile part transformed into a precarious aerial seesaw. The engineering is a thing of beauty in itself.
Over, on and through this steel ballet move the two performers, each perversely determined to occupy the same physical space. Michele Weaver is an impish seductress with a penchant for dangling by her heels from a letterbox 15 feet up. Mike Ashcroft is a ringer for the young Ernie Wise, an earthbound bloke whose sense of outraged normality - and hilarious lack of head for heights - repeatedly tip him into apoplexy. The convulsive little jig he makes out of the act of patting his pockets to search for lost keys is a comic gem.
The gist of the plot is a tussle between this ill-matched pair over the boundaries of personal space, and as such, it goes beyond amusing spectacle to offer some pointed observations on co-habitation. There is real paranoia as Ashcroft - who likes things just so - clocks the fact that Weaver is mischievously rearranging his beloved, shiny black shoes. We know how much he loves them from a version of the old music-hall mirror routine: a natty cakewalk before the (non-existent) glass, wearing a shoe on the end of one arm as a third leg.
The relationship runs the gamut of outright war, seduction, rejection, reconciliation, conjugal boredom, and finally, after a nerve-biting spat at opposite ends of the swinging skylight, a lasting equilibrium. I suspected a technical hitch at the climax of the performance I saw. I think we were intended to gasp over the aerial finale, and instead there was black-out and a fumble. But this did not detract from a most original and compelling piece of theatre.
Slack Dance - flak dance, smack dance, anything but - has done that rare thing. It has found a way of transcribing the unsayable into a brand new form. There'll be more chances to catch up with it early next year when the show tours nationally.
If it's true that success breeds success, then, on paper at least, Girls on Tap couldn't go wrong. Take themes from the three most lucrative dance shows of recent years - Riverdance, Tap Dogs and Hot Shoe Shuffle - add a pinch of Spice, and hey presto, you have the formula: a variety show with lashings of old-fashioned singing and hoofing, pepped up with Nineties girl-power. But whereas its templates benefited from massive pre-publicity - Eurovision, telly specials, overseas sell-outs with screaming fans - Girls on Tap is working from a standing start.
Did the producers really expect to fill the 1,700-seat Southend Cliffs Pavilion merely by offering shameless lookalikes of a certain all-girl group? There was a Scary one, a Posh one, a bubbly black girl, a dippy blonde with silly bunches. They may be aiming downmarket, but even Dolly the sheep wouldn't fall for this kind of marketing clone. Sure enough, the theatre was well-nigh empty, and the show's mostly very young cast proved themselves true pros in the face of every performer's worst nightmare.
They were also battling with choreography as stale as old popcorn, from which the fashion parade of steel-capped footwear provides a nice distraction, ranging as it does from hi-top trainers to purple platform knee-boots. A preoccupation with teenage fashion dominates the girlie themes that link the songs and dialogues, many of them conducted in a nightclub ladies' loo, to which the girls retreat to bitch, preen and stuff their bras with tissue paper. Some of this is quite amusing, but it is when the loo attendant bursts into song, flinging off her overalls to reveal a series of ludicrously flashy outfits, that the show takes off. Chanteuse Christine Glen is a knock-out, whether crooning like Sinatra, growling like Bessie Smith, or coming on strong like Tina Turner. There is fine vaudeville, too, from Yolanda Clarke, and a titillating nose-to-nose catfight on the nightclub floor, if you like that kind of thing. All Girls on Tap needs to run and run is an audience.
'Girls on Tap': Birmingham, Alexandra Theatre, (0121 643 1231). Mon- Sat; then touring to Dec.