With just one TV movie to his name (1999's Annie), stage director and one-time choreographer Rob Marshall makes his movie debut on the $40 million musical "Chicago"...

What were the challenges of bringing "Chicago" to the screen?

The hardest thing was that it was created specifically for the theatre, originally called "Chicago: A Musical Vaudeville". That meant all the songs were presentational. Bringing that to film was a very tricky prospect, because you don't have an audience. Things like "A Chorus Line" are very hard to bring to the screen, so we needed a strong conceptual idea and that was the biggest problem.

They've been trying to make this film for the past 20 years. People toyed with ideas of how it could be done and there were a lot of scripts and a few directors along the way.

One script started with a construction worker coming out of a sewer trap singing "C'mon babe!" Wonderful, isn't it? So we shot that and said, "That doesn't work." It really was a problem: how do you get into this movie? How do people start singing? How is that natural?

Did you consider "Chicago" a high-risk venture?

For Miramax it was, very much so. I kept having talks in my trailer about how this was high-risk and that I had to keep moving fast. It scared them, but I think they were also excited by it as well.

The thing about movie musicals is that there have been some brilliant ones, but when they're bad, they're really bad - big white elephants. So people would get to thinking it didn't work anymore. This is a true American art form and it was so sad to have it disappear. But over the past 20 years or so, there have been these animated musicals and that was acceptable. I find that you just have to know how to present them. You have to find a way for people to digest the music and have it be natural.

The burden of credibility must have weighed heavy on the actors' shoulders...

Catherine, Renée, and Richard all have unbelievable instincts about everything. So when they say something feels wrong, or "I feel funny saying this", you listen. And I did. Every time.

This was collaboration on so many levels because they brought the characters to life in a way that I could only have imagined. To find actors who could do this with the gritty reality of "Chicago" and at the same time play the world of Vaudeville and still make you care is unbelievable. These are not likeable characters, in many ways, but you love these characters because of the actors. That's why I think this film works, because of these flexible actors who can do anything you ask them to do.

"Chicago" was never meant to be simple fun and frolics, was it? How did you envisage the social satire element?

In 1926, when "Chicago" was originally written, it was relevant in a major way. It was written by Maurine Watkins, who was a cover reporter in Chicago at a time when all these killings were happening. All these jazz slayings. And these killers were becoming huge stars out of it.

One of my favourite lyrics in the piece is in "Nowadays" when they say "In 50 years or so, it's gonna change". But it hasn't changed. It's unbelievably relevant now. It's the Jerry Springer Show when they're up there dancing and singing and people are applauding them. It's celebrity boxing. It's all that. That's why we wanted to do this movie. In addition to entertaining people, it says something very important.

"Chicago" is now playing in London. It opens in the rest of the UK on Friday 17th January 2003.