04/07/2012 04:18 BST | Updated 04/07/2012 07:55 BST

3D Katy Perry: Part Of Me Review - Shows A Star Singing While Her Heart Is Breaking... (TRAILER)

Obviously, from the off of this accidentally interesting, behind-the-scenes film, there is a ghost in the machine, a Banquo at the banquet, and his name is Russell Brand.

katy perry

Katy Perry's rollercoaster year was caught on camera, the highs and lows

Katy Perry: Part of Me was shot over the course of a year, 2011, two months after she’d married Brand in a wedding ceremony officiated by an Indian elephant as far as I can make out, and then done the 21st century blushing bride thing, of setting off on a record-breaking tour around the globe.

Such an enterprise would be tiring anyway – it is abundantly clear just how hard Perry works, physically, emotionally, musically to keep her many fans happy, and thus her career in the stratosphere – never mind when you’d really rather be elsewhere, enjoying the cuddles of a newlywed, never mind when you’re frantically asking for days off “to rescue my marriage” as Perry jokingly claimed, to hollow laughter from her worried entourage.

katy perry

Katy's team show their loyalty to their employer

It is clear where Team Katy’s loyalties lie. “She flew all over the world to meet him, she did everything she could,” says her manager, and there is almost a pantomime hiss from the cinema audience when Brand first turns up in shot, but you can’t help but feel a bit sorry for the bemused Brit in the face of this relentless behemoth of a touring machine.

He starts off grinning like a bewildered Cheshire cat, joining in one of those pre-concert group-bonding rituals that the Americans seem to go in for, judging by Bieber’s recent biopic. I can’t see Mick and Keef going in for this kind of thing, and certainly not someone with the ironic eye of Brand.

“That was amazing,” he gamely reports after one concert. I’m sure it was, but after the 110th time? No wonder he’s made his apologies by then.

Gradually, Perry’s post-marital glee of making it all work, balancing the needs of millions with the needs of a freshly-married couple to, call me old-fashioned, go shopping for furniture turns into an evidently solitary campaign to keep gathering ye rosebuds while ye young fans are out there, and make good on all the years of struggle to the top, faithfully captured here.

katy perry

Katy Perry: Part of Me shows the effort involved in bringing together a tour of this scale

By two-thirds of the way through, it is clear that there isn’t really anyone waiting at home anymore, something Perry isn’t afraid to show, all from her side of course – tense telephone calls and sad looks into the middle-distance, all while the fans wait for their dollars' worth of concert excitement, and the fabled meet-and-greets.

This sadness no doubt contributed to the evident fatigue she felt – at one point she could barely scrape herself off the chair to meet yet more fans, but does make for a far more interesting film, with a conundrum at its centre.

Question as to how much someone can be affected by heartbreak when you’re that famous? Is the sorrow such that you completely forget there are a million other people happy to see you, or is your public persona so dominant that everything, even the breakdown of those eternal vows made less than a year before, seen through the prism of how best to keep the show on the road?

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Katy Perry gets increasingly tired as her tour rumbles on

I suspect the answer is both, ie. it’s all a bit crap really, but the cash and the clamour certainly help take your mind off it, and a million people happy to see you helps keep one person’s lack of interest in perspective, as Princess Diana and a million other much-loved but abandoned beauties discovered before her.

One scene late in the film shows her wiping her tears dry and slapping a smile on her face literally a second before she goes on to dazzle yet more concert-goers. Documenting this rollercoaster chapter in her life, professional peak, personal despair, has given Perry a unique chance to demonstrate her humanness as she proved, but also, that she’s up there with the best of them for evolving into a real showbusiness trouper, one who can smile, and sing, while her heart is breaking.

3D Katy Perry: Part of Me is in UK cinemas tomorrow. Watch the trailer below...