Overnight success can seriously damage your career. There's the personal disruption, of course, but more importantly, there are huge expectations for your next project and enormous pressure to get it out quick. As a result, it won't be as good as the first, because you had years to perfect that and there were no expectations.

Connie And Carla Do LA is Nia Vardalos's follow up to the surprise smash hit of 2002, My Big Fat Greek Wedding, which she wrote and starred in. That film was originally a play, which meant the script was the product of years of work and audience feedback before it got near a film studio. Connie And Carla, by comparison, feels rushed, with unbelievable characters and a predictable plot.

Vardalos plays Connie, one half of a disastrous musical double act. She and Carla (Toni Collette) are determined to make it in showbusiness, despite the assurances of their boyfriends that their talents have no beginning. They witness a mob killing, which forces them to go on the run, so hide out as a drag act in a gay club. Naturally, as female impersonators, they are a sensation, but things become complicated when Connie falls in love with Jeff (David Duchovny), who thinks she's a man.

The plot is unashamedly derivative, like a female Some Like It Hot, but the twist is enough to make it a promising concept. There is a problem, however. The story doesn't make sense.

After the murder, a police car arrives and the girls think they are saved, until the cops turn out to be gangsters in disguise. It's a moment that sums up the lazy plotting, as the audience know immediately they're not kosher, otherwise there'd be no movie. Besides which, there's no reason for the gangsters to impersonate police.

The film's message is one of tolerance and self-acceptance, but this is equally unconvincing. We're told how awful it is for people to stare at drag queens in the street, but surely anyone wearing a sequinned ballgown and feather boa is expecting a little attention. We're told that Jeff isn't gay, and yet he falls in love with Connie, while thinking she's a man. Worst of all are the speeches about female body shape, which may be well intentioned, but have nothing whatsoever to do with the story.

Despite this, Connie And Carla is a lot of fun. The musical numbers are a camp triumph, with songs from Cabaret, Jesus Christ Superstar and Yentl and a cameo by Debbie Reynolds that can only be described as fabulous.Vardalos and Collette are always watchable, despite a lot of mugging and slapstick and there are a number of genuine laugh-out-loud moments.

Connie And Carla is certainly an amusing way to spend a couple of hours, but don't expect too much. After all, it's not easy to follow an overnight success.