Sara Foster is probably best known for her roles in popular teen soap 90210 and the 2004 comedies D.E.B.S. and The Big Bounce. But she’s ditched the glitz for darkness in her latest film, the brooding horror Psych 9. “I was in a really dark headspace,” she tells Matt McAllister.

What was your initial reaction when you read the script to Psych 9?

Well, when I first read it I thought there’s no way I could commit to it in the way I needed to. I was scared, I was intimidated. So I passed on it, I said I couldn’t do it!

Then they were getting down to the wire – the main actress had dropped out, production was starting, and they were seeing different people. So I auditioned for the movie… It all happened really quickly. They came back and said, “Your audition tape is good, come on, you can do it!” And everyone in my life said, “If you’re this scared, that means you gotta do it!” So I got on a plane to do it.

It’s certainly less light or glamorous than your previous work.

Yes, though this was shot before 90210. I’ve been on the show for a year and a half, and I did Psych 9 right before that.

But it’s not that I never wanted to do a dramatic role. It’s just it’s not so easy to get the chance. Very seldom do people in my position get the opportunity to carry a film like this. These kind of roles go to Naomi Watts! It’s definitely changed my confidence now, knowing I’m comfortable doing a movie like this. And you get better as you work. So the next drama that I do, I’ll hopefully be even more comfortable.

But it was a real commitment. I was in a really dark headspace for two months. That’s the only way I know how to stay in the moment. If I was to drift for a day, I wouldn’t be able to get back there. Some of those scenes we had were so heavy and so draining.

Your character is in a constant state of anxiety the whole time isn’t she?

Yeah. And some of those scenes like the abortion sequence... it was horrible! Hard on my soul. But I’m proud of it and the commitment we all made.

Your character, Roslyn, isn’t the typical horror victim…

No, she’s not a damsel in distress. And the film doesn’t deal with gratuitous blood and guts or maiming and killing either. The violence is very subtle. You’re on a psychological ride with her the whole time instead; it’s kind of a whodunit, you’re trying to work out who is killing all these girls.

Are you a fan of horror movies in general?

No. I don’t like violence. I think it gives people ideas. It’s really hard for me to watch people being tortured, or that type of film. But I don’t think that applies to our film – I mean, I like watching our film! I did cover my eyes a few times, but I like films where you have to think, where you’re constantly trying to put the puzzle together and analyse them.

You mentioned that this was a psychologically challenging role. What kind of preparation did you do to get yourself in that mindset?

I didn’t have much time as it was all so fast. But once I committed to doing the movie, I broke down the script heavily with my acting coach and we basically spent three or four days, eight hours a day, completely shaping who this person is. How she dresses, how she walks; I set puzzles for myself. There was so much about her that wasn’t in the script. I had to fill in the blanks for myself.

I also watched a lot of movies, such as The Ring – there was something about Naomi Watts’s character that I drew a little bit from. And what I really did was just immerse myself in the film. I shut myself off from everything else. I didn’t speak to anyone for two months! We were working 16-hour days, six days a week – I became this person, I really did. I went through a bit of a depression, that’s for sure.

Did shooting in an old hospital in Prague add to the atmosphere?

For sure! I don’t know if I would have felt the same way if we were shooting in Los Angeles. Shooting in Prague definitely added to the coldness, the eeriness, the isolation.

Prague in the winter is a scary place! It’s a beautiful city, but there’s so much history there. You can just feel it in the air. And some of our locations… I mean one of the locations we shot in was a mental institution! Oh my gosh, it was so creepy!

What was the hardest scene to shoot?

Some of the therapy sessions with me and the doctor, played by Cary Elwes, were difficult. Because you’ve really got to nail them. There’s no room to ‘sort of hit it’. You’ve really got to hit all the emotional beats. I felt a lot of pressure.

And the abortion scene… that was hard! I was on that gurney for five hours, and I didn’t move. I didn’t want to get up between takes and break the rhythm, you know?

How did Andrew Shortell’s directing style differ from other directors you’ve worked with?

The difference with Andrew was it was his first time. He felt a lot of pressure on himself, so he was all the more eager and all the more prepared. Because this was his chance.

He knew what he wanted and I had to face knowing that he would never move on until he got it. But he also made sure to give me the space to do what I needed. I don’t know how other people work, but for me when a director smothers me and gives me too many notes, I shut down completely. And in a role like this, if you shut down you’re not getting the scene. So Andrew and I worked well together.

You also worked with a couple of ‘80s legends, Michael Biehn and Cary Elwes….

It’s funny, it’s always the more experienced actors who have the least attitude and no ego. You don’t feel like they’re standing above you, looking down on you.

I didn’t have that many scenes with Michael, but Cary was wonderful. He was there for me the whole time if I needed him. He would come up to me and say, “You nailed that!” That was so good to hear from him!

How did the budget and pace of shooting compare to other projects you’ve worked on?

Well, movies are being made now for, like, a million dollars. And this was a seven or eight million-dollar budget, which is actually a lot – and in Prague you get a lot for your money. So to me this actually felt like a big budget! I’ve done things that are way more guerrilla style than this.

What’s next for you?

I’ve got a movie coming out called Demoted, which is a comedy with Sean Astin, Michael Vartan from Alias and David Cross from Arrested Development. It’s a fun comedy.

And there’s 90201. It’s a good time to be on a TV show! You can do both TV and movies now. It used to be a no-no to do both, you had to do one or the other.

Would you be tempted to star in another horror?

Listen, I would love to. If the right thing came along I would definitely be open to it. But it’s hard… I’m a very happy person and in order to do a film like this again I would have to go down the same route, which is to shut off. And I’m getting married at the end of the year so life is a bit different now!

Psych 9 is out on Region 2 DVD on 11 October 2010.