The Imaginarium of Doctor Parnassus is one of Terry Gilliam’s most accomplished movies; unfortunately it’s also his most tragic. During the shooting of the film, its star Heath Ledger died from an accidental overdose of prescription pills. After the total shock of the catastrophe sunk in, the question of finishing the movie began to surface, and Gilliam in his inimitable way conceived a premise that actually works.

In the movie Ledger portrays Tony, a charming and mysterious man who is saved from hanging to death by members of a traveling show, headed by Dr Parnassus (Christopher Plummer), who offers audience members the chance to transcend mundane reality by passing through a magical mirror into the fantastic universe of limitless imagination. Gilliam brilliantly uses the mirror to change Tony into three new personas, performed by Johnny Depp, Jude Law and Colin Ferrell, finishing the scenes that Heath Ledger was unable to do.

Where does your inspiration come from?

Director Terry Gilliam © Sony Pictures Classics

The biggest thing I find is we are so overwhelmed by information now through the media and internet, I don’t know how people maintain their own individual identity anymore. I was lucky. I grew up living in the country with only radio so I’d imagine a lot of things and that’s, I think, where it comes from.

We used to be able to say “I want people to switch off.” I’m trying to get people to learn to be alone. Turn it all off. Just be with yourself and see what’s there, see if there’s anybody home.

How did you come up with the idea to finish the film after Heath’s tragic untimely death?

Director Terry Gilliam © Sony Pictures Classics

Once you decide to carry on, which is the hard part, you say “Alright, he goes through the mirror three times. Three actors.” On just a totally pragmatic level, there was no way to get one actor to replace Heath. I didn’t want to do that anyway. And there’s no way to get a great actor to turn up at the last moment. We’re making a movie. People have schedules. They’re all busy working. The fact we were able to squeeze Johnny, Colin and Jude’s schedule into our schedule in some way was kind of a miracle. You’ve got three possibilities out there and it was actually just more interesting as well.

LV Woman (Maggie Steed) and Imaginarium Tony #1 (Johnny Depp) © Sony Pictures Classics

I thought you needed three A-list actors to replace Heath. He was that good. That was my attitude. But once you make the decision that people’s faces can change on the other side of the mirror, that was basically simple. I didn’t rewrite much. There’s a lot of little things that I’ve done but nothing of any substance. The dialogue was all written before. That speech that Johnny Depp gives about the young dying, some people think that’s a eulogy to Heath. No. That was already written. This film was about mortality. That’s the great irony of the whole thing – mortality being a central part of the story and look what happens. I supposed one’s got to be careful of what one writes at times.

When they go into the mirror, did you ever consider, aside from Heath, changing the other actors as well so that you’d have more of a through line?

No – let’s do Johnny Depp’s scene for a moment. Here’s my logic, my reasoning for what we do. You go through the mirror and you’re actually in the imagination of the Louis Vuitton woman, as we call her. The temple of shoes, giant shoes with a Buddha for shoe enlightenment ultimately. And suddenly this guy turns up, “That’s the guy. I dreamed you would look like that.” That’s a line that I added. I added that line to explain [the difference in actors]. She has dreamed he looks like that, so now he can be that.

With the three actors, how much did you want them to emulate Heath because you could really tell they were playing his role?

Imaginarium Tony #2 (Jude Law) © Sony Pictures Classics

I chose people who were close friends of Heath’s so they knew Heath. So that’s to start. And then we gave them all DVDs of what we’d been able to assemble of what Heath had done so they could see what he was doing, how he was moving and how he was talking and everything. And then, they arrived. No time to rehearse. Do it. It was really brave of them. It’s extraordinarily brave because they could have just fallen flat on their faces.

Imaginarium Tony #3 (Colin Farrell) © Sony Pictures Classics

I thought maybe this was the way we could pull this thing off. I wasn’t certain. And they just came in and got to work. We had one day and 3-1/2 hours with Johnny – that’s all – to do everything he did. I watched it the other day and said “How the f**k did we do that?” But because he came, he was totally on the ball, we just started shooting. That’s what’s wonderful because I think as actors they all got to escape from their own egos. They suddenly were doing something for Heath outside themselves and they just breathed Heath in and spewed him out.

You’re always the guy that surprises us. What surprises you?

Oh, actors surprise me. I’m always begging for surprises. Well, Heath did the big one. That was the kind of surprise I don’t need, but he surprised me.