(M) **

Director: Adam Shankman.

Cast: Tom Cruise, Julianne Hough, Diego Boneta, Catherine Zeta-Jones, Russell Brand, Alex Baldwin, Malin Akerman, Paul Giamatti.

THE '80s was a different time. It was an era when rock music reached its debaucherous peak, double denim was an acceptable thing to wear, and musicians singlehandedly punched a hole in the ozone layer thanks to their hairspray consumption.

The thought of an '80s-set musical will have some people quivering with genuine excitement and others thinking "this should be good for a laugh".

It's this double-sided view that ultimately undoes Rock Of Ages - is it a heartfelt homage to the power of music during the last time that rock gods walked the earth or is it a tongue-in-cheek pastiche of the "people were so silly back then" variety?

Unfortunately the film tries to do both while doing neither properly, creating a shifting and uneasy tone that never quite finds a groove for its largely plotless story to sit in between the power ballads and hair-metal anthems from the likes of Journey, Bon Jovi, Poison, Def Leppard, Extreme, and Pat Benatar.

The year is 1987. Country singer Julianne Hough plays Sherie, the "small-town girl livin' in a lonely world" who took a midnight bus away from her backwoods home to go in search of fame and fortune on Hollywood's Sunset Strip.

There she meets Drew (Boneta), who also dreams of being a singer and works at the legendary Bourbon Room, run by Dennis (Baldwin) and Lonny (Brand).

As Drew and Sherie's love blossoms against a backdrop of '80s hits, the biggest rock star of them all - Stacee Jaxx (Cruise) - arrives at the Bourbon Room to play his final show with his band Arsenal before going solo.

These story details make for the leanest of plots. A sub-story about an anti-rock protest group that parodies Tipper Gore's Parents Music Resource Centre gets little traction, meaning Rock Of Ages can barely even summon the cliched "rally to save the club", Empire Records-style plot. Instead we get a sappy boy-meets-girl romance that's as tired as it is predictable, while the potentially intriguing character of Stacee Jaxx who ultimately goes nowhere.

It's the shifting tone that really lets the film down. One minute we're expected to absorb a passionate duet as an emotional moment between two characters; the next minute a similar duet is supposedly played for laughs, yet is delivered in a similar fashion. Ultimately you could laugh at the whole movie because it's so cheesy, and the movie struggles to find a balance between when it's being heartfelt and when it's sending itself up.

But what about Tom Cruise, I hear you ask? Can he sing? In these days of auto-tune, anyone can sing, but on the face of it The Cruiser does a decent job. It's certainly his most interesting performance since Collateral, and the first to feature him wearing a bejewelled codpiece, leather chaps and nothing else.

His experience does help steady the film, as do good performances from Zeta-Jones, Brand, Baldwin, Akerman and Giamatti, who all seem, for the most part, to be in it for a laugh - they don't seem to be taking it seriously even when the film does.

The Brand-Baldwin pairing is particularly good once it gets going, and everyone has a sing (even Baldwin and Giamatti) and there are a few genuinely funny moments.

It's when the songs kick in that the film works and is actually pretty enjoyable - it's just a lot of the pieces in between are less effective.

At best, Rock Of Ages is like many of those big rock anthems of the '80s - kind of fun, but lacking any real substance.