Interview: Christopher Nolan, director, and Leonardo DiCaprio, actor

If audiences are eager for another slice of Nolan's unique and highly stylised storytelling, so too is the Hollywood studio that stumped up more than $150 million to fund the film. Nolan's last outing, the aforementioned Batman sequel, racked up more than $1 billion at the worldwide box office, making it one of the most successful films of all time.

The director's phenomenal critical and commercial success has granted him carte blanche when it comes to crafting the films he wants to make, no matter how complex. And Inception, the story of a man who steals people's most valuable secrets by entering their dreams and plundering their subconscious, is certainly complex.

"This is a high concept film, and it's a film that's working on a multitude of different levels simultaneously," says the film's leading man, Scorsese favourite Leonardo DiCaprio. "And it's kind of a hard film to pitch. It's more of a film that you really need to experience." There is a lot of truth in DiCaprio's words, and there's no doubt that the studio paying for the project parted with the cash without knowing entirely what it was going to get. Such is the power of Chris Nolan.

"Chris is absolutely one of the best filmmakers out there," enthuses DiCaprio, "and the truth is that it's hard to enter his mind in certain instances when he's talking about how this film is all going to piece together conceptually. But what he works with you on as an actor, and what's so vitally important, is the emotional narrative of your character and what your character means in that plot."

This, it seems, is the secret to Nolan's success. Most critics and fans reference the cool, super-stylised worlds he creates, like his dark and moody Gotham City in Batman Begins and The Dark Knight, or the fascinating plot structures that underpin the likes of his 2000 movie Memento (or indeed Inception), without giving due notice to the emotional truths that propel the movies. Whether audiences are aware of it or not, Nolan's Batman, for example, proves so engaging because he is a fundamentally flawed and vulnerable man, in spite of his innumerable gizmos and gadgets, and superhuman courage.

"With Inception, people will think that the film is beautiful," says DiCaprio, "but they will also see some powerful moments. You feel on the edge of your seat with the intensity of the plot structure, but there is also this psychological, sort of surreal journey that you go on with these characters that means something. And that's very difficult to do as a filmmaker. Very difficult. And so few people can actually pull that off."

Inception's story revolves around DiCaprio's character, Dom Cobb, the leading light in a criminal network, who specialises in navigating a path through people's dream state, travelling their subconscious mind, and extracting information. His emotional journey through the film, meanwhile, sees him yearning to get back to his children - he has been accused of murdering his wife (played by Oscar-winner Marion Cotillard) and cannot return to the US - and a normal, everyday life. Cobb is offered one last job with the carrot that, if he pulls it off, he will be grounded again and reunited with his family.

The story idea first came to Nolan around ten years ago, although it wasn't until he spoke to DiCaprio that he found the emotional strength in the tale. "I have always been interested in making a film about dreams, really since I was a kid," offers Nolan. "And I have been trying to write and to finish this script for years. As I wrote it over the last few years it became bigger and bigger. I tried to write it as a small film because dreams are very intimate experiences but what I found was that once you address the idea of dreams, anything becomes possible and the world of the film naturally expands into something quite big.

"I was quite fortunate to have been able to make large-scale films like Batman Begins and The Dark Knight and combine that scale of filmmaking with my human and intimate interests. So we try to do a lot of different things in the movie."

So where did Nolan's long-standing interest in dreams come from? "The key thing that I have been fascinated about with dreams is the idea that when you are experiencing a dream you are experiencing an environment, and talking to other people, and it is real, but it is also this idea that your brain is creating all of those things that you are also perceiving.

"You are creating a world and perceiving it at the same time, and that is fascinating, and a weird creative feedback loop. What the film addresses is: what if you could get into the middle of that process when the dream belongs to somebody else? What if you could interrupt that, take over the creative role, create the world of the dream and bring somebody into that?"

This is what Cobb and his team - which includes Ellen Page's Ariadne, and Joseph Gordon-Levitt's Arthur - do, although the vital plot point involves planting an idea in the mind of a powerful executive, played by Batman Begins' supporting actor Cillian Murphy.

"When I was writing the film," says the 39-year-old director, "the very early drafts specifically, there were a lot of other films around exploring similar themes." The most notable include Dark City, a shadowy sci-fi delving into the concept of the collective unconscious, from director Alex Proyas, and The Matrix trilogy, directed by the Wachowski brothers. These films first found life around the turn of the century.

Nolan's breakout movie, Memento, released around the same time, about a man unable to store new memories, touches similar ground. Even the director's follow-up, 2002's Insomnia, deals with delirium caused by a lack of sleep. "Some of those films were an inspiration, of course," says Nolan, "but what was absolutely vital for me in this movie is that we aim for a true sense of realism."

The action sequences that pepper the film are riveting, and Nolan shot as many scenes as possible in-camera rather than relying on special effects and green-screen filmmaking, allowing the dream worlds and the real world to intermingle. "There are a lot of computer graphics and visual effects but for a film of this scale there are about 450 effect shots instead of about 1500 or 2000, which you would normally see in this kind of film; we always try to give the effects guys something in camera to be building out, something to work with."

Indeed, the film involved a great deal of globe-trotting, taking in England, Japan, France, Morocco, Canada and the US. "Travelling all round the world and shooting in a lot of different places helps with achieving some level of reality," Nolan says. "In the trailer you see a city collapse into the sea, a key element of the film, and Ellen and Leo were really on that beach; they were in the frame, they are walking out of the sea and it is all real. It was shot in Morocco. It is a real shot that has just been enhanced and added to and I think that is when visual effects can do their best computer work."

Interestingly, Nolan says, the human mind is often compared to a computer, which he feels is an inadequate analogy, "because the brain is capable of more than we will ever know." He is right. His own brain, in particular, is capable of more than many of us could ever dream. v

Inception is on general release from 16 July

This article was first published in Scotland on Sunday July 4, 2010..