Dir. Tom Vaughan. US. 2008. 98 mins.

A bit like Las Vegas itself, frenetic romantic comedy What Happens In Vegas offers some diversions that are mildly entertaining but really just postpone an inevitable outcome (in Vegas the house always wins and in rom-coms the bickering stars always get together in the end). Though the sexy pairing of Cameron Diaz and Ashton Kutcher should get the Regency Enterprises production off to a good start, the odds seem long that this brash farce, steered by British director Tom Vaughan, will end up as anything more than a mid-level summer counter-programming earner for worldwide distributor Fox.

Fox releases the film wide in North America (with a PG-13 rating) this weekend, dropping it into a marketplace already heavy with well-received rom-coms but putting it head-to-head only with the differently targeted Speed Racer. The studio will be hoping that Vegas can grab a relatively balanced male-female audience before the arrival a few weeks later of the presumably more female-skewing Sex And The City.

A slew of other territories open day and date with the US but Fox may have to work harder to secure an audience in the international marketplace. Although some of Diaz's recent comedies have performed much better internationally than domestically, Kutcher is less of a draw outside the US, so the marquee pairing will lose some of its appeal beyond American shores.

In spite of its title (part of a slogan used in the US to promote the gambling capital of the world), the film only seems like a Las Vegas tourist board ad for its first half hour. After introducing Kutcher's aimless party boy Jack and Diaz's recently dumped control freak Joy, screenwriter Dana Fox (The Wedding Date) quickly sends her characters off for the wild Vegas weekend during which they meet, wed, acrimoniously break up and then win $3m.

Back in New York, Jack and Joy ask a grumpy judge (Miller) for a divorce and a ruling on who gets the money, but the judge decrees that the couple must try to make the marriage work for six months before the cash can be assigned.

While the contrivance seems like something out of a vintage screwball comedy, what follows is too mechanical to justify that label. With Jack and Joy trying to trick each other into providing grounds for a lucrative divorce, the film goes through a series of battle-of-the-sexes set-pieces packed with bruising slapstick and lame sarcasm but nothing much resembling witty banter.

Vaughan - who started in UK TV and made his feature debut with gentler 2006 rom-com Starter for 10 - keeps things moving at a suitable breezy pace but doesn't manage to find an emotional arc for the characters within the episodic narrative. As a result, the story's emotional climax produces a jarring last-minute change of tone.

The always-game Diaz throws herself into the physical comedy but can't make the uptight and insecure Joy very likeable. Kutcher is equally willing to try anything for a laugh, but he is beginning to look a tad too old to pull off the naughty little boy charm that is his usual rom-com style.

The supporting cast members make the most out of some fairly standard genre roles, with Rob Corddry (from Blades of Glory) playing Jack's less-handsome sidekick and Lake Bell (Over Her Dead Body) Joy's less-pretty best friend.

Director

Tom Vaughan

Production companies/backers

20th Century Fox

Regency Enterprises

Worldwide distribution

20th Century Fox

Producers

Michael Aguilar

Shawn Levy

Jimmy Miller

Arnon Milchan

Screenplay

Dana Fox

Cinematography

Matthew Leonetti

Production design

Stuart Wurtzel

Editor

Matthew Friedman

Music

Christophe Beck

Main cast

Cameron Diaz

Ashton Kutcher

Rob Corddry

Treat Williams

Dennis Miller

Lake Bell