1. Where did you grow up?
New York City, on the Upper West Side.
2. What was the young Martha like?
I was tall, blonde, relatively silly, and fairly independent from a very small age.
3. What made you want to become an actress?
I don't know, it just kind of happened when I was very little. My mother [Shelley Plimpton] was an actress and she worked a lot in the theatre world. We didn't really pursue it very hard, my mom was not really a stage mother. But then as I got older it just became something that I naturally wanted to do and it just kind of stuck.
4. If you hadn't been an actress, what might you have done?
I have no idea. I might have been some type of organiser.
5. What was your first big break?
There have been quite a few actually. The first movie I did was called The River Rat, I was 12 years old and had quite a large role opposite Tommy Lee Jones and Brian Dennehy. But I wouldn't really call that my big break. I did a commercial for Calvin Klein that actually helped get me that job, so maybe that could have been it?
6. What do you consider your career highlight?
When we did Tom Stoppard's Coast of Utopia at Lincoln Center - there aren't too many experiences that can top that one, for me. And Raising Hope, but more because of the ways in which it has changed my life.
7. Any regrets?
Even if I had them, I wouldn't tell you.
8. What was the first thing you saw on stage that had a big impact on you?
Well the first thing I saw was Hair on Broadway, because my mother was in it. In fact she did the show while she was pregnant with me, so that music is really in my DNA. We went to the theatre a lot when I was little. My mother didn't often have money for a babysitter so she would just take me along. By the time I was six I'd been to the theatre too many times to count.
9. And the last?
I did just see Ghosts here and that was really quite good. I really loved seeing Lesley Manville on stage and thought the whole cast was excellent.
10. Have you managed to see anything else in London?
Yeah, I saw Fortune's Fool at the Old Vic when I got here. But I haven't had the chance to see much else because I'm really tired after work.
11. Why did you want to get involved in this production?
Robbie [writer Jon Robin Baitz] and I have been friends for many years and we had been wanting to do this play together for a while, but the timing was never good because I was working on a series. When he called me about the Old Vic production it was just perfect timing.
12. Could you tell us a bit more about the character you play?
Brooke is the daughter of a California Republican. Her father is a typical California Conservative, an actor who became an ambassador, who became the chair of the Republican Party. He's a Ronald Reagan type guy. Her mother is a very patrician and helped to orchestrate this very carefully constructed life that she and her husband share. But Brooke has written a tell-all book, and they're not happy about it.
13. Are you enjoying working alongside Sinead Cusack and Clare Higgins?
Absolutely - it's been a fabulous experience so far.
14. Any rehearsal room mishaps?
Oh I couldn't! It's a private space. I can't tell you those things. You're going to have to wait at least 20 years and some of us are going to have to be dead first.
15. What do you hope audiences take away from the play?
From my perspective the play is really about artistic licence and family responsibility; how much do you owe the people you love, and to what extent should you lie to protect them? I hope they walk away from the play having had an experience that allows them to understand something in a different way. That's all you can really hope for when you're doing a play.
16. What are your feelings about making your West End debut?
I'm thrilled to be here, really thrilled, and I'm excited to play in front of a London audience. I've never had that experience before, and audiences all over the world are different. I feel very fortunate because it's an American play, so there's a little bit of pressure off in that regard. It's not like people are going to be criticising my accent. I hope.
17. How are you finding London?
Oh, I love it! I've been here before, but never for so long as this. My only criticism is I would appreciate having a slightly easier commute to work everyday.
I'm from New York where everything's on a grid, everything's a straight line, but here it's like this crazy, zig-zag, nutty, 15-dimensional arrangement. It's wild. But that aside I feel like London and New York have a very close bond.
18. What's your favourite theatre anecdote?
Oh God, there's thousands of them! I like the one Clare Higgins told me the other day about John Gielgud. They were doing some kind of rehearsal exercise and the director said, "I want everyone to come out and say or do the scariest thing you can thing of." So the cast came out and made these awful faces or cried blood curdling screams. Then finally Gielgud walked out on stage and said, "We open in a week."
19. If you could swap places with anyone for a day, who would it be?
Anyone? Probably a fisherman in Bali - I'd like the peace and quiet.
20. What's next for you?
I'll be going back to New York after Other Desert Cities, and then I'm waiting to find out if Raising Hope is coming back for a fifth season, which is up to the gods of television. But I'm trying not to look too far into the future, because you just never know, you just never know.
''Other Desert Cities runs at the Old Vic until 24 May.