How did you get involved in "The Cripple of Inishmaan"?
Daniel Radcliffe: I met Michael Grandage for the first time when I was 14, when my agent was first starting to get me to meet a few people. I met him and talked about theater and the fact that I wanted to do it. Then years go by, I worked with Rob Ashford on "How to Succeed," and of course Rob is a child of the Donmar theatre in London as well. He was brought up through there, has directed loads there, and worked with Michael a lot. I guess Michael got good reports from Rob, and then Michael came and started talking to me and saying, "I'm putting together this season." He said that he wanted me to be in the third play of the season, and then he gave me five plays to read and we talked about them. To be honest, as soon as I read "Cripple," already being a big Martin McDonagh fan as I was, I was like "it's going to be hard to beat this one."

You will play "Billy" as a young man with cerebral palsy. How did you prepare?
Dan: I've got to learn a potentially tricky accent, and, obviously, the physicality of the role. I'm having classes at home with a lady called Janis Price, who's a vocal coach but she also has a very, very, very mild cerebral palsy. It's very slight so we're working on basically timesing what she has to the power of 10. In the play it's never specific, they don't ever mention what is wrong with him. They just say, one bad arm, one bad leg, and he's shuffling. So then it was a matter of really going through the play and extracting what information we could. After we identified it as cerebral palsy, that's when we got in contact with Janis. She told me about the condition, the mechanics of it, what it is and what you can and cannot do with your leg or with your arm. It's really been a matter of working out how brilliant you become with your right side. Learning about the disability has been really interesting, and my mission for it is that I hope that people who have the specific type of cerebral palsy that I have—because there's a term, it's hemiplegia—I hope they come and see the show and go, that's authentic.

What about this play attracted you?
Dan: It's such a challenging play because most of the humor is derived from cruelty. It's all about these characters being relentlessly cruel to Billy, not even cruel in a malicious way, that's just how they talk to him. They've called him "Cripple Billy" all his life, it's natural for them to make a joke about his arm, make a joke about his leg, take a ****, be horrible to him. That's just so run of the mill for him. For me, the interesting part of Billy is trying to express the difference between his inner life and his outer life. The frustration over the fact that they're so at odds with each other.

It's interesting because Billy is an orphan, while other characters you've played have complicated family backgrounds.
Dan: Well, let's count—Billy, David Copperfield, Harry, Maps [in "December Boys"]—this is my fourth orphan. Which is kind of interesting for somebody's who's had a really lovely family background. My parents are great. Chris Columbus maybe said it best when I had my first audition for "Potter," when he just said, "Dan's a really happy kid but he's just got something that looks slightly haunted about him sometimes," whether I mean to or not. And I think that's maybe my orphanish quality.

You're writing a screenplay. How's that going?
Dan: I finished my first pass at the thing I'm trying to do. I immediately sent it off to ["Kill Your Darlings" director] John Krokidas. He's the only person I've shown it to. I just said, get your red pen out and he actually gave brilliant stuff. He was giving me these notes and I was going, oh that's very clever. That's something I would definitely like to do, because it's just fun, and I want to direct. I think it's probably easier to write something yourself than to try to convince somebody to give you their script as a first-time director.