Part of me was fascinated by the idea that I would only get next week's episode a week in advance and wouldn't actually know where I was going with it, until the script landed on my mat. But, part of me wanted to know what was going to happen.

Interestingly, this character [Doctor Nash] is probably closer to me than somebody like the evil Sir Godfrey in Robin Hood or Lord Blackwood who wants to take over the world in Sherlock Holmes. This is a character that's English, he's based in London, and so it's closer to me than a lot of stuff I've been doing recently.

I'm not a writer, inherently. Most of the writers I've met have stories they need to tell. I don't have that. I'm an interpreter. I like getting a script, seeing a character and thinking, "Oh, wow, I know what I can do with that."

When you're making a psychological thriller, what you need to do is have an audience on shifting sand so they're never quite sure where they are.

If you think about Shakespeare, you remember Richard III and Macbeth before you remember Ferdinand, whose role is just to fall in love and be a bit of a wimp. I love the baddies. More important, though, is making the baddies somehow, weirdly, understood.

In the movie, you have to decide as an actor how you are going to give a character presence. You can't really move, walk, and talk like yourself. This creates something so you have to find something "other".

The important bit for an actor is the actual shooting of it, because the minute the shoot ends, it's got nothing to do with you anymore.