The outrageous comedy Frankie Go Boom, from writer/director Jordan Roberts, tells the story of Frank Bartlett (Charlie Hunnam), who tells himself that he’s holed up in the desert to write, but in reality is just hiding from his family, namely his brother Bruce (Chris O’Dowd). A reckless but charming addict, Bruce has always enjoyed secretly filming Frank in all sorts of compromising positions and sobriety isn’t making their relationship any better. And as much as Frankie tries to move on with his life, family just keeps sucking him back in.

At the film’s press day, actress Lizzy Caplan – who plays Lassie, a young woman at a crisis point in her life, that finds a connection with Frankie – spoke to Collider for this exclusive interview about what attracted her to this role, playing with the levels of emotion with her character, the sweetness of the relationship between Frankie and Lassie, having to wear an edible bra, and the most challenging scene for her to shoot. She also talked about her upcoming Showtime drama series, Masters of Sex, with Michael Sheen, and just how far it will go. Check out what she had to say after the jump.

Collider: How did you come to this film?

LIZZY CAPLAN: The script was sent to me, and I think my agent or manager had read it and said that it was funny. And so, I read it and loved it, and then had to go and do the normal channels. I auditioned a couple times and fought for it.

Was there something specific about this role that appealed to you?

CAPLAN: Yeah, it was a couple things. One of them was that this girl was inherently sweeter than a lot of the characters I’ve played, and I like to switch it up, whenever I can. But mainly, it was the first few scenes that my character has. I knew they’d be very challenging, and I like to challenge myself. So, I was like, “Yeah, I’ll go and cry uncontrollably,” which is really not my forte. I just knew it was something that was going to freak me out, so I signed right up.

This girl really is a mess, when we first meet her. Did you try different levels of her emotion, to get that right?

CAPLAN: Yeah, I think there’s a lot of freedom with this character because, in that moment, she is so insane and so drunk. It was all the things that allowed me to throw reason and a linear arc out the window. I could kind of just do whatever I wanted. And then, I looked to (writer/director) Jordan [Roberts] and Charlie [Hunnam] to rein me in, if need be, but they were all for pushing it further. I’ll speak for the whole cast in saying that a lot of us were playing against type with this movie. It’s just so out there and so strange, and was such a short time commitment, that movies like these are no-brainers. Of course, I’ll go and mess around for 19 days, and get to do something that I don’t normally get to do. It was really funny, and everybody gave a really funny performance.

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How did you view Lassie? Did you feel like you could identify with her?

CAPLAN: I like to look at the people I play as shades of myself, maybe pre-therapy. Now, having gone through a lot of therapy, I can identify people’s issues. And so, I knew why she was in this position and I knew why she felt this way. Her fiancé, who she thought she was going to marry, totally betrayed her, and that would suck. Plus, her father is a completely insane person, so she wasn’t parented properly. I don’t think she really ever had an opportunity to cut loose and be the wild one. So, people who are forced to be more buttoned-up, when given the opportunity to really go nuts, it’s so much scarier because they take it so far. That’s how I saw her.

No matter how outrageous things get in this film, the sweetness between Frankie and Lassie really keeps things grounded. What was it like to develop the relationship between your characters?

CAPLAN: I think that any project needs a little bit of both. A super hardcore drama really benefits from moments of levity sprinkled throughout, and vice versa. The audience gets bored when they’re just hit over the head with the same thing, and they want to see the characters, on screen, doing something that’s a little breather from the insanity, especially with this movie, of what they’ve been doing the entire time. I always get jealous of the people who get to be the craziest on set and have the weirdest shit to do, that day. So, I had to hold my tongue and be the most normal one, in a bunch of scenes. But, I think it paid off, just because Lassie’s moments of craziness are right up there with the other characters.

When you actually had to wear the edible underwear, what went through your head?

CAPLAN: It was awful, but it was another challenge. I like being put in embarrassing positions because it’s the reason why I wanted to be an actress. I want to try different things and things that make me uncomfortable. I don’t think about what it’s actually going to be like, showing up on set wearing that stuff. I was just like, “Oh, that’s a really funny idea. That will be funny when I see it in a theater.” And then, you go into the wardrobe fitting and you’re putting the thing on, and it just sucks. People are taking pictures and critiquing the candy bra to figure out what they can do better, and that was awful. But, Charlie was basically naked the entire time, so I wasn’t by myself.

Were there any wardrobe mishaps?

CAPLAN: The bra was always falling apart. They had two or three of them, in different states of disrepair because that night spans a long time and, at some point, he does attempt to eat parts of the bra. But, it was very securely taped. I felt pretty protective. And then, Whitney Cummings had to put it on, a few days later, so we were in the same boat and could help each other out with it.

With all of the crazy things you had to go through, in this movie, were any of them more challenging?

CAPLAN: The scene that I was most worried about was the scene in the car, where I wake up and I’m really upset. The sex scene stuff less so, just because I knew I was going to be with somebody who would be equally as uncomfortable, in the same situation. That was a strength in numbers kind of thing. But, I didn’t want to blow what I thought was such an amazing comedic moment, on the page, so I put a lot of pressure on myself for that scene.

What attracted you to the Showtime drama series, Masters of Sex, and just how far will it actually go?

CAPLAN: It goes far. It goes crazy far! The explicit sex scenes were certainly not what drew me to it. There’s this strange thing about doing nudity on camera now, with the internet and everything. I’ve only done it on one other job, which was True Blood, and yet it seems like something that I do all the time. At least, people seem to think that. It was more that I was drawn to the character of Virginia Johnson, who I find to be the most fascinating woman. And a huge part of her personality and who she was, was a woman who was completely comfortable with her own sexuality, at a time where that was almost unheard of, in the Midwest during the 1950's. It’s crazy that she even took lovers that she didn’t want to marry, eventually. That was her whole thing.

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So, I knew, even going after the point, being comfortable with that kind of explicit material would be necessary because it’s just at the core of who this woman was. It’s why she was so helpful to [Dr. William] Masters. Why their studies were so successful was because she understood sexuality, more than he did. He understood science, and she understood the human element of it. And she’s such a complicated woman. It’s, by far, the most challenging part I’ll ever play. It has been the most challenging, up until this point. And the story is just amazing and riveting.

I think people will probably be tempted to say, “Oh, they took it really far. It’s a cable show. Of course, they’re turning it into this overly sexualized thing.” But, it’s based on a biography of the two of them and all of the stuff really happened. We’re not amping it up. It really was that strange, and they were doing it for this greater purpose. They really believed in the science of the project. I really believe in this project, so it’s like, “All right, if I have to be on the internet naked for a few more years, then whatever.”

Is it nice to have someone like Michael Sheen, as your co-star, to go through it with?

CAPLAN: Oh, he’s the best! He’s so awesome and so game for everything that we’re going to have to do. We’re going to be really getting into some stuff, so luckily we get along with each other. It would be a nightmare, otherwise.

Frankie Go Boom opens in theaters on October 12th.