Having revived Batman, director Christopher Nolan turns his attentions to the mind games of his earlier work - but with an A-list cast and a mega-budget. He talks to Michele Manelis.

When Christopher Nolan delivered his breakthrough film Memento - a film so original in its backward storytelling - it left many of us confused. Since then, he's made two Batman flicks which have turned them into the greatest superhero franchise in popcorn cinema history. They have grossed more than a billion dollars worldwide and won Heath Ledger a posthumous Academy Award for his role as the Joker.

Now comes the English-born director's new film Inception, another mindbender which will once again force audiences to question their notions of logic and morality.

Starring Leonardo DiCaprio as the leader of a team who steals the thoughts and secrets of others by entering their dreams, this high-concept story is Nolan's most ambitious film yet.

"The last secure place for our ideas or thoughts has always been in our heads," smiles the immensely smart Nolan. "But that's no longer the case with this technology, with this skill that these guys have, so that's really the jumping off point for the story. It's the kind of movie the audience shouldn't know too much about going into the theatre. They shouldn't know what to expect."

The recession has hit Hollywood hard with studios making deep budget cuts. But Nolan apparently remains a sure thing. All his films have been box office successes (Memento cost only $5 million but made $25 million in the US alone) but there are reports that the daring and highly cerebral Inception cost $150 million, a risk indeed, even given the presence of the always assured Leonardo DiCaprio as its lead.

"We did come in under budget," is all Nolan will say on the subject. Nonetheless, the project progressed in fits and spurts, and he spent the best part of a decade honing the script. "I first pitched the idea to Warner Bros after I shot Insomnia but I wasn't ready to finish writing it. I didn't think it would take me nine more years to finish, though. It's a story I've grown into. Looking back now, I wasn't emotionally ready to finish it when I initially began."

Inception was shot across the globe including Morocco, France, England, Japan, the US, and Canada. "It served the story well to shoot in many different locations because it gave the movie a realism it might not otherwise have had," Nolan says.

Despite the multi-layered storylines, Nolan sees the film more simply than some of its audiences might. "I see Inception as a traditional, classic, heist movie. What these guys do within the architecture of a person's subconscious is what people do in the real world. The stakes in the dream worlds are as significant as what's happening in reality."

The movie's haunting ambience and highly stylised look is complemented by the always-intense DiCaprio who consistently serves up authentic performances. "Leo brings an incredible amount of emotional veracity and focus on the truthfulness of the life of the character and how that informs the story. He's extremely demanding in that respect and he certainly made it a film that I feel extremely emotionally connected with."

The human subconscious is familiar territory for Nolan. Memento had Guy Pearce's character plagued with short-term amnesia, therefore unable to retain memories. Nolan followed with Insomnia, in 2002, starring Al Pacino, a detective who is unable to sleep while on a case in the perpetual sunlight of an Alaskan summer.

"Specifically, I've been interested in dreams, really, since I was a kid. I've always been fascinated by the process of dreaming. The idea that your mind, when you're asleep, can create a world that it perceives simultaneously; that you've literally created a world in your dream and you're not aware that you have and you're perceiving it, as if it really existed - that, to me, has always been the most profound demonstration of the infinite potential of the human mind. It was something I always wanted to find a way to explore through story, through film."

The cast includes the Oscar-winning Marion Cotillard, indie queen Ellen Page, and Joseph Gordon-Levitt.

Leading man DiCaprio sees Nolan as a rare director. "Chris is obviously pulling some extremely bold concepts in a major Hollywood movie, and that's rarely done. He's a visionary film-maker and I had to approach the film much differently than any other movie I've done. It was months of conversations and a lot of one on one interaction because you're dealing with a very surreal, endless, infinite world of the human subconscious.

"We had to learn the Chris Nolan set of rules for his dream world."

Cotillard took some convincing to sign on. "When I read the script the first time, I had to read it two more times," she laughs. "And then I was immediately obsessed with it."

It must have provided some challenges. "I had to surrender my desire to understand everything and just to be driven by Chris.

"So I told myself that I didn't need all the answers and I trusted him."

DiCaprio is not worried by suggestions that the film is too complicated for the average cinemagoer. "I don't think that's always important. I think that's an underestimated quality. In order to make a film that makes you extract your own meaning or to have different interpretations of an ending or what things represent in a film, that's a part of the experience of going to a movie. It's supposed to be your own unique interpretation," he says. "To me, that's part of the whole experience of going to the cinema, being able to discuss it with friends and discuss your interpretation of what the characters represented and what they meant and what the film was trying to accomplish.

"To me, if I go see a film and there's no discussion afterwards, I obviously know it was pretty shitty," he laughs.

The movie also stars Ken Watanabe, Cillian Murphy and Michael Caine, who have appeared in past Nolan films. But the director's most frequent collaborator is his wife of 11 years, Emma Thomas, who worked as a producer on all of his Hollywood films, and with whom he is raising three children in Los Angeles.

She admits getting Inception made was a challenge. "Generally, when you look at the films that are being made, for all sorts of obvious reasons, studios want to play it safe. Movie-making is a very risky business. There's a lot of money spent on making a film and marketing it. Sometimes that works and sometimes it doesn't. We were lucky that Warner Brothers saw something really special that they wanted us to make. "And it can work. Look at Avatar. That came from James Cameron's mind. It wasn't based on any material remotely like it out there.

"So these things can work."

Nolan is returning to the franchise that made him a Hollywood heavyweight. His brother Jonathan - who has co-written most of his films - is writing the screenplay for a new Batman movie, but the director won't be drawn into discussing an Inception sequel.

"I refuse to answer the question on the grounds that I don't want to jinx the film. My fingers are crossed, and I'm hopeful that the film is going to be a success for the studio, because they really supported me making a film that I'm very, very passionate about. But I'm very, very superstitious."

Nolan's also a bit incredulous about his climb from unknown indie film-maker to top Hollywood director. He occasionally wonders if it's all been a dream. "At the risk of sounding cliche, the truth is, I love what I do and I love my job, and there is an aspect of that being dreamlike. It's hard for me to credit the fact that I've managed to be able to do what I love, I mean, even get paid for it," he said.

"There's certainly some weird fear in the back of my mind that I'm going to wake up and find myself back where I started. But at least then I'd have all my scripts worked out."

Who: Christoper Nolan, director
Films: Doodlebug (1997), Following (1998), Memento (2000), Insomnia (2002/I), Batman Begins (2005), The Prestige (2006), The Dark Knight (2008).
Latest: Inception
When & where: Opens at cinemas July 22

- Additional reporting, AP