A bedazzling sing-off by six women, each determined to wrest back control of her own narrative, Moss and Jamie Armitage's production is slick, witty, and so frenetically charged that resistance is pretty much useless. What's behind the glitter and the gloss, the astonishing vocals and the seductive strut, is in reality not much more profound than the Spice Girls' rallying cry of "Girl Power": it's a case of clever branding rather than serious substance. But it undeniably works: an audience dominated by young women and girls, many of them watching with their mums, whooped their appreciation, faces glowing. This may be feminism-lite, but it ignites powerful passions.