Sarah Bolger was picked from thousands to play Sabina in the new Stormbreaker film about a teenage super-spy.
Based on Anthony Horowitz's best-selling book of the same name, the film tracks the adventures of two school friends.
Newsround's Claudine Spera spoke to Sarah about what it was like starring in the new film.
Are you a fan of the books?
I read Stormbreaker before I heard about the film and then I read it again when I knew about plans for the film.
How did you get the part of Sabina?
The usually way, which is through my agent.
They flew me over to London - I live in Ireland - I had a meeting with the casting director. I did some scenes with them and after that they rang up the producer Marc Samuelson and brought me over to meet him which is quite unusual. Usually you just meet the director and go home so it's brilliant and a great sign to meet the producer too.
I left England and about a week later then they rang me up and told me I'd got the part. I couldn't believe it when they started reading out the other cast members - I was like 'What?!'
What's your character Sabina like?
Sabina isn't in the first book Stormbreaker - in fact she doesn't come in until the third book. There are two girls in the whole series so [author] Anthony Horowitz did a poll to see who was liked and everyone seemed to like the Sabina character more than the others so he added her to the screenplay which was brilliant.
She is a very spunky character. She's really gutsy and she was great fun to play. And I got to do some stunts! She's the lead character Alex's potential girlfriend - you can just tell something's going to happen in the next book.
Did you like her as a character?
I loved her - she was brilliant.
Is she a spy too?
No - she's in school with Alex and it so happens that she gets to help him on his mission.
Did you get to act in any action scenes?
I got to do some brilliant stunts. They closed off Piccadilly Circus in London so Alex and I could ride a horse around the streets weaving in and out of cars and buses - I had to learn to ride especially for the part. Mickey Rourke threw me off a building so I had to learn how to fall - I had to be on a harness and flung off the building. It was great fun and I'd do it again - the set was specially built for it.
Did you get to play with any of the gadgets?
No I didn't get to play with them - I got the horse! I saw a few gun props lying around though.
Loads of big actors are taking part in the film - what was it like working with them?
When I met Mickey Rourke he was such a gentleman. The scene we had was action packed and I had to pull him back and start kicking him and he was a really nice.
I met Ewan McGregor and I was star struck - he's gorgeous! He was lovely and he was talking about a film I was in, called In America, and said how much he loved it.
What was it like on set?
The set was quite different from any other set I've ever been on because of all the stunts. And on action films there is a lot more waiting around because they have to rebuild the set and for safety reasons. I had a great stunt supervisor - she was just brilliant. She was Angelina Jolie's stunt supervisor in Tomb Raider.
Did you have to go to school on set?
No because most of it was done during the summer holidays so that was brilliant.
Will you carrying on studying or do you want to take up acting full-time?
I am definitely going to finish school but I want to be an actress.
There are more books in the series - would you like to play Sabina again?
I would love to! But in the books they don't grow-up and we do so we might not get to play them again but I'd love to do it again.
Have you seen the finished film?
No, not yet. I went to London two weeks ago to do a voice dub and I got to see a good bit of the film. It's brilliant - very funny.
What was your favourite scene?
Myself and Alex had a great time in the school scenes because everyone around us was kind of our age and everyone came up to us and asked us what it was like. Hanging out with people our own age was good fun.