Britney Spears, Wembley Arena, London

the time seems to have passed in a nanosecond, but Britney Spears has packed a lot of living into the two years since she last took her show on the road. Heartbreak and alleged breakdown, marriage, divorce and reinvention - the pink-clad princess of pop has lived the kind of emotional roller-coaster that would ordinarily underscore the life of one four times her young years. The colt-limbed Lolita who once writhed lustfully along school corridors urging us to hit her "One More Time" has taken more than her fair share of blows. And, while her fall from grace has been spectacular, Britney herself isn't entirely blameless.

So it is with some degree of trepidation that the audience, an extra- ordinary demographic made up of ageing tweenies, pre-teens, over- excitable dads and homosexuals, greet the leather-clad dominatrix who opens the doors of the Onyx Hotel stage set, "where all your darkest secrets" will be made real. And not without good reason, because, from the start, the show is an erogenous zone in search of a climax. Despite the presence of leather-clad dancers and a creepy MC with a passing resemblance to Jack Nicholson's Joker in Batman, the potentially dark and mysterious theatrics on stage are undermined by Britney's routines, which come across as half-hearted and disingenuous.

For all the pyrotechnic trickery and flamboyance on display, the Onyx Hotel show is singularly underwhelming, and Britney's performance, hailed as being her raunchiest yet, has all the sexual charisma of a soft toy.

Certainly, the tousled blonde locks, the pneumatic bosom and the breathless nasal vibrato that has become her signature style are intact. But as the evening progresses, there's an unshakeable apathy evident in the audience, which suggests that, at only 23 years of age, Spears is already a spent force. And her stage antics are only faintly reminiscent of her idol and sometime best friend Madonna, whose infamous Girlie Show set the standard for young female performers seeking to make the transition to sex bomb.

Like Madonna's tour of a decade ago, the show bears the same degree of wanton contrivance. But whereas La Ciccone had the charisma and self- assurance to manipulate and control her audience, Spears flounders in the same context. The songs - a quick trip through a back catalogue of 15 undeniably catchy tunes, interspersed with dreadful bits of video drama (added, one imagines, to give the evening some kind of narrative fluidity), are undervalued in their delivery. By committing herself to an overly frenetic choreography, Spears is forced to rely on lip-synching to carry the tunes - and the results are atrocious. She squanders her one opportunity to reconnect with her audience by offering a jazzed-up rehash of "Oops! I Did It Again" that completely misses the mark.

Performing in the "Mystic Lounge", trussed up in a micro-sized baby- doll outfit, Spears contrives to give the impression of a footballer in drag. She makes all the right moves, but behind all the grinning, gurning and vocal gymnastics, Britney's eyes are dead. It's been a roller-coaster journey to the Onyx Hotel, but you get the very strong feeling that once there Britney can't wait to check out again.

Touring UK and Europe to 6 June (www.britneyspears.com)