Q: What did you like about the script?

A: "I was excited when I read Cody's script because it was solid and different. Her dialogue is unusual, with a brand of slang that is descriptive and creative. She has, effectively, patented her own kind of slang. It's a horror comedy with heart. It's completely unique. As soon as I started working on the film, I realised how special it was going to be."

Q: What is it like playing the plain girl?

A: "I loved playing the plain girl because I didn't have to have my hair styled. I was able to be natural. I didn't have to wear much make-up, which was fantastic.Often, I'd rather be the plain girl because it is interesting when a character is not based on how I look."

Q: Do you think the film's portrayal of high school is realistic?

A: "Yes, because it shows how everything is over-dramatised at high school. You tend to overreact to things. Obviously, I don't know any girls at my high school who have, literally, become zombies and eaten boys, but figuratively, metaphorically, yes, I think you can compare girls to man-eating zombies sometimes. They can be very manipulative."

Q: Do you believe the film has anything serious to say?

A: "Absolutely. It's about leaving your childhood behind and growing up."

Q: What was it like working on a Cody screenplay?

A: "Great, because she is quite fearless as a writer. She is always very bold and politically incorrect. I'm a big fan of her work. Having her around while we were making the film was great because it meant that she could change things a little if needed. She's not desperately attached to what she's written and is a wonderful person to have around when you are making a film."

Q: What would you say audiences can look forward to?

A: "I think they will enjoy the complexity of the story and will get a more interesting package than they expect. This film is unique. Boys will come out of it with more respect for girls, and girls will feel really positive about themselves. Women will walk out of the theatre and feel, 'Yeah!'. It is an incredible movie for women. Not a typical genre horror movie, it involves a lot of different elements. It's real, dramatic, hilarious and frightening."

Q: Your last film was the colossal hit Mamma Mia!. How did that change your life?

A: "It made me marketable. People became more familiar with my work. So many people saw it and I developed beautiful young fans everywhere. It is really gratifying to get all their dedications and fan letters. Of course, I am much more recognisable now and have many opportunities I would not have had without Mamma Mia!. People in the business have a lot of respect for me because I worked with Meryl Streep. "

Q: What are you working on in Italy?

A: "We are making a film called Letters to Juliet with Vanessa Redgrave and Franco Nero, a romantic, quirky movie that is nice and entirely different from Jennifer's Body. It is such fun shooting in Tuscany. It wouldn't be half as romantic if we weren't shooting in Italy."

Q: Have you learned a great deal during the past few years from these older, talented actresses?

A: "I learned a lot from Meryl Streep. She's good at separating her life from her work and is incredibly focused on what she does. I have learnt from many extraordinary women who have treated me like gold. I also worked with Julianne Moore (on Chloe), another recently made film. Through working with these women, I've gone up a notch myself. I'm moving in the right direction in my career. They are the best. I am so lucky."

Q: Was acting a big passion for you when you were younger?

A: "It was. I was very outgoing and loud. I liked attention when I was little and I put on plays in our living room. I did summer programmes at the theatre school in our town. I always found acting fascinating. But I wanted to be a singer for a while, on Broadway or an opera singer. Then, when I was 15, I merged acting and singing. By the time I was 17, I had stopped singing and had become entirely focused on acting. By the time I made Mean Girls, I was in the business for good."