While Tilda Swinton's casting caused some controversy with the comic's fans, she's getting terrific reviews for her performance. Seeing Swinton in a superhero movie is a bit of a surprise, but she didn't hesitate to accept the role. "Hell no," she laughs. "Scott [Derrickson, the director] told me about the film he wanted to make, and that was good enough. I'm a big Marvel fan, and I never dreamed they'd find some corner for me. But I really wanted to see this movie the way he described it: this huge tent-pole megalopolis about creation rather than destruction."

Tilda Swinton as The Ancient One

Derrickson adapted the role of the Ancient One with Swinton in mind, veering from the comic's depiction of a standard Asian male master. Swinton says that the character was deliberately changed to avoid racist undertones. "There's a kind of misunderstanding, which I hope the film will make clear," she says. "Scott made this very clear decision with the whole team to change the Ancient One from the rather, what they considered, offensive racial stereotype in the comic books - this kind of Fu Manchu, ancient man sitting on top of a mountain. They made this decision to not perpetuate those racial stereotypes. The fact that they take the liberties that they do in filmmaking, I think it dignifies the comics and it says, 'Yeah, this is a strong enough, robust enough source. We can bend it, it's elastic, it's bouncy!'"

More: Read a review for Doctor Strange

Swinton is also excited about future Marvel films that will push issues of diversity even further, with movies centred around female and black superheroes. And she's happy that Doctor Strange takes the genre deeper with a focus on the power of the mind. "There's a lot of people who can benefit from learning these skills," she says. "The Ancient One is teaching perfectly normal people how to still their minds and choose options. I just love the perspective that somebody of thousands of years of life has. I love the possibility of not sweating the small stuff or the medium stuff, or really not sweating stuff at all! I've been fortunate enough to sit at the knee of all sorts of fabulous people like my grandparents, and that's what I see age can bring: perspective. It's just about perspective. And that essential knowledge that fear and ego are to be lived beyond. They're the things that screw things up."

Watch the trailer and clips for Doctor Strange: