The hope is, of course, that the film has an inbuilt audience. With the casting largely predicated on five young and attractive women who know how to blast a rifle at robots and cut the gullets of baby dragons, the movie is high fantasy-meets-girl power, hyper realism fused with extreme surrealism. It's a movie within a movie, or not, depending on what you want from it.

'We made the movie on two levels,' says Snyder. 'If you want to go on a ride, on a romp, that movie exists. But I also like the idea of going for a coffee with your friend afterwards and talking about the juxtaposition of this and the iconography of that. That's fun, too.'

The idea behind the movie had its genesis in a script Snyder wrote in the early 1990s, when he directed commercials. One of the characters in that screenplay is a girl who is forced to dance in front of thugs, but escapes into some fantasyland in her head while doing so. 'When I re-read the script, much later, I thought, 'God, this sucks'. But I liked this one character, this one part. I liked the mechanism of it, and I thought there was something there.'

Snyder and Shibuya hashed out an elaborate, if sometimes befuddling, plot. Snyder recalled a scene from the original Planet of the Apes movie, where a partial lobotomy is taking place. 'I thought, 'that's horrible'. I just felt that even worse than being killed is having the you that is you removed from yourself. The only construct where we could put [these characters] in that position was in an insane asylum in the mid-60s in upstate New York or Vermont. That was how that world got created. Then Babydoll came along, and she had a crazy imagination and did a bunch of crazy s***.'

The dancing character, Babydoll (played by Emily Browning), is transformed into a hot action chick with blond ponytails, fluttery eyelashes and pink pouting lips, and brandishing a samurai sword. That, of course, is her alter-ego; she is actually undergoing a lobotomy, a process that causes her to mentally retreat into a bordello, from where she escapes once again to fight everything from demons to mummified soldiers. She is joined on her adventures by other female inmates of the asylum/brothel: the protective Sweet Pea (Abbie Cornish), the feisty Rocket, (Jena Malone), the vulnerable Blondie (Vanessa Hudgens) and the loyal Amber (Jamie Chung). Between them, they wield sub-machineguns, M4 assault rifles, shotguns, flintlock pistols, bayonets and a tomahawk.

Those high-octane action scenes are a nod to the girls-kicking-butt sensibility in a spate of recent movies: Chloe Moretz played an 11-year old vigilante in 2010's Kick-Ass; in the Oscar-nominated True Grit, Hailee Steinfeld plays a girl out to avenge her father's murder. In the upcoming Hanna, Saoirse Ronan is a 14-year old assassin.

'I think it's exciting,' Deborah Snyder says of the new trend of girl-killers in movies. 'For a while I heard it said that women and action don't really work. I feel like it can work as long as the action is good and if the women are believable. If that all works, then the movie will work.

'What I like about our girls is that they're not just tough. They're not trying to be men. They're just as tough and they fight hard, but they do it with femininity.'

The girls fight in corsets, high heels, lip gloss and false eyelashes - but Deborah Snyder defends those wardrobe choices by saying they are more feminist than sexist. 'The costumes are sexy, but they are owning them, turning them on their head,' she says. 'They're not trying to be masculine action heroes. It's a really great thing that they can cry, be bonding, have a sisterhood, but still shoot big guns and kill lots of people. I think that's pretty cool.'

Because they are such an integral part of the story, Zach Snyder intensified his search for the right actresses. He has never been one to gravitate to the big names, instead finding interesting talent who may just be hovering near the cusp of the big time. 'We saw 200 girls,' he says. The first one he signed was Cornish. 'I'd always been fascinated with her work. She's such a serious actress, I knew she would elevate the rest of the cast. She has this quality of innocence and vulnerability, but there's so much more there.'

The actresses jumped at the chance to work with Snyder, whose work on 300 set him apart as an iconic filmmaker. He is known in the industry for tending to every detail, from scores to wardrobe. Also, he has something of the star maker in him: Gerard Butler was virtually unknown before 300.

'The culture of working on Zach's films is very open, supportive and collaborative,' says Tyler Bates, who composed, arranged and produced the music for Sucker Punch. 'He manages to cull these elements together and hits the mark that is Zach Snyder's brand. He's one of the most imitated directors of the last few years, inspiring people by the look of his films, the treatment, the colour.'

Sucker Punch opens on Thursday