When Cassandra Magrath auditioned for Wolf Creek, she didn't think she had much of a chance. How could anyone get a role in a horror movie, she told herself, when she can't produce a scream?
''I really can't, and I've tried,'' she says. ''It's physically impossible for me to do it. I can yell, but I can't do that high-pitched sound.''
To her relief, she managed to keep her secret, and she got the part. ''It was never really required. I hadn't quite understood that it wasn't that kind of film.'' Its terrors were achieved in other ways.
Wolf Creek, in which she played an English backpacker who makes some unfortunate choices when it comes to outback travelling companions, is her best-known movie, but it's only one of scores of projects in a career that began at the age of 11.
Right now, she's rehearsing for a production of Fat Pig, by American playwright, screenwriter and director Neil LaBute.
We meet at Hammer And Tong, a relaxed and friendly eatery just off Brunswick Street in Fitzroy.
Magrath orders lamb ribs with ricotta, peas, preserved lemon, zucchini and mint. I settle for corn and zucchini fritters that come with avocado, manchego, spinach and a tomato relish, topped with an egg.
Her new play is the first production from Lab Kelpie, a company that has a very specific audience in mind, Magrath says.
They want to appeal to people who have never been to the theatre before, or to people who have been dragged along to something that they haven't enjoyed.
Fat Pig is a very accessible work. ''It's funny, clear and modern, but also quite complex.'' It's about a man drawn to a woman he can't imagine being seen with. She is big and unselfconscious and disconcertingly funny about herself, and he falls in love with her, yet he tries to keep their relationship a secret.
Magrath plays Jeannie, a woman who has also been involved with this man. He has been stringing her along and, when she discovers she has a rival, she doesn't take it well.
Jeannie does and says some horrible things, Magrath says, and as an actor, she needs to find a way to understand how this happens. ''I could easily have played Jeannie for laughs, but that's really not what's written. I think where she is coming from is frustration … and she takes it out on the wrong person.''
Magrath might not be playing for laughs, but with LaBute's script, she knows they'll come: the trick is never to expect them.
''If you deliver a line and it doesn't get a laugh, you can think, 'Oh, I've failed', and that can really throw you off.'' You can't predict or depend on laughter, but you have to be able to leave a space for it.
As far as she's concerned, theatre is the ultimate experience for an actor. ''Learning the dialogue, living the arc of the play, presenting it to people who are right in front of you: and you will feel whether they like it or not. There's nothing like it.''
Beyond that, she says, ''I want to master all the different areas: theatre, film, TV, soap. I don't care. They're all very different, and it's about refining your skills so that you can do them all.''
Yesterday she was filming an episode of the TV series Wentworth, the new version of the classic Prisoner, in which she plays a journalist, not an inmate.
Before our lunch she was doing a confectionery voiceover. After lunch it's back to rehearsal. She has to get back across town, so it's a bit of a scramble, but we manage to fit in dessert: a delicious combination of strawberries, white chocolate and slivers of lemon verbena granita. And she has a chai latte with soy and honey, to take away.
She always knew that acting was what she wanted, she says. Various members of her family have been dancers, and she and her siblings sang and had dance lessons, but she was the one who wanted to take the next step, at the age of 11.
Her mother said that was fine, as long as two of her five siblings, the ones closest in age to her, had the same chance. All three were signed up, all three went to their first auditions, and all three got a part.
Her brother got a role in a Bell Shakespeare Company production, and her sister got a part in Scrooged, the musical. Magrath landed a role on the children's TV series Ocean Girl, about a mysterious young woman who could communicate with sea creatures.
Her siblings had fun, but they didn't want to stay with it, she says. A lot of the young actors she worked with are lawyers and doctors now. But she always knew she would stay the course. ''I've had really good role models.''
Jeffrey Walker, a young actor who was in Ocean Girl and played her brother in another kids' show, The Wayne Manifesto, ''was so professional and perfect and showed us all how it's done''.
When she went on to play Sigrid Thornton's daughter in SeaChange, she had another example to follow. ''Sigrid was just the same.''
Most actors, she says, are pretty level-headed about what they do. ''I've heard stories of people who get a bit carried away – 'It's not Hollywood, darling, bring it back a little' – but I've never worked with anyone like that.'' And she doesn't think this sort of thing would cut much ice in Australia anyway.
Wolf Creek, written and directed by Greg McLean, came at a good time for her, she says. ''It was huge for me, and I'd just missed out on a really big television contract. It came down to the last two and I was really devastated.''
The shoot was a terrific experience, she says, and she was very excited about being in a horror movie, even though she can't bear watching them. ''I don't enjoy being scared.'' Even so, she's keen to see Wolf Creek 2, which premiered at Venice to good reviews.
She went to the United States after the release of Wolf Creek, found an agent, and started to look for work. ''It was fun, and I learnt a lot, but no audition was successful.''
In the end, she couldn't afford to stay. Maybe she was a bit young, she says. She might do things differently if she went back.
Now, on top of everything else, she's studying for a bachelor in film production. She wants more options and more ways to support herself and stay in the same field.
''If you really love something, you don't want to give it up. I've had enough jobs outside the industry to know that I don't want to work outside the industry.''
■ Fat Pig opens at Chapel Off Chapel on October 9.