Ben Wheatley's ambitious all-killer, no-filler thriller "Free Fire," is set in a Boston warehouse in 1970s where an arms deal goes disastrously wrong. Among the cast of very colorful characters are IRA operative Chris (Cillian Murphy), smooth-talking go-between Ord (Armie Hammer), and an off-the-rails South African gunrunner Vernon (Sharlto Copley). The calm in the midst of the storm of testosterone and gunfire is Brie Larson's Justine, an intermediary who tries desperately to keep the situation from spiraling out of control. (Spoiler alert: It still spirals out of control.)

Larson, a recent Oscar-winner and current "Kong: Skull Island" star, channels her considerable charm into a character whose motivations remain murky and whose dialogue is minimal at best. If there's a beating heart at the center of the bloody mayhem, it's her.

So it was a huge thrill to jump on the phone and talk to Larson about what it was like being in "Free Fire," her upcoming directorial project, and whether or not she came up with a back-story for her character. At the end of the conversation, I tried to slip in a question about her role in "Captain Marvel" (which just secured its directors) and it didn't go well. She gave me what can only be described as a Nelson-esque "ha ha" and said, "Oh, sorry, I've got to give the phone back." And then we were done. Sigh.

Moviefone: This movie has so much action that it doesn't leave much time for us to get to know your character. Did you work out a back-story with Ben Wheatley or talk to the other actors about it?

Brie Larson: I did talk with Ben about it a little bit. But he's interesting in that, when he casts you, he completely trusts you to just create it and bring it and do it. It's kind of scary because the training wheels are off but in another way it's exciting because he gets to run with whatever idea you have. I always come up with some sort of back-story, especially because Justine doesn't speak that much. She's more observing and listening and trying to blend in, so you need to know where she's coming from. A lot of the film we would do improvised takes and that would make it trickier. Because you have to know who your character is to be able to improve off what the dialogue is that is already existing.

That's interesting, that you were able to improve given how tight, structurally, it seems.

The whole structure of the film -- and I'm pretty sure most of the dialogue that's in the film -- was scripted. He just does a thing that's one take scripted, one take improvised. It's fun because it loosens up the dialogue on the page and makes you feel free and that things are a little bit messy. I think Ben's secret agenda is to make every actor feel totally confused and uncomfortable, especially during a movie like this. Because he wanted to show the reality of fumbling and not knowing what is going to happen next. You can't do that unless you put your actors in a little bit of a hot seat of not knowing what was going to happen.

I know that Wheatley was inspired by the American crime movies of the '70s. Was that appeal what got you involved or was it more working with him?

It takes a couple different perfect elements to get me to sign onto something, because it's such a long journey making a movie. Part of it is I have to want to explore the character, I have to be interested in who she is and discovering her. But the other part is the movie itself and in particular when the movie is over what are you left with and what are you thinking about? What is it making you question? And I think that the idea of cinema as this place that has idolized and glorified action and violence and guns and ego. There's a really big history, we've made that something that's cool. I like the fact that this is the coolest uncool movie or the most uncool cool movie that you'll ever see. There's something about the '70s that's deeply iconic and interesting but at the same time we're not that savvy. We're bumbling and scrambling on the floor and making mistakes constantly and the blood and the violence isn't glorified is what interested me in the film.You've spent a lot of time in the '70s between this and "Kong: Skull Island."


How did your character change throughout the filming of "Free Fire"?

I think what I discovered is that, in order for Justine to get her agenda across, it just requires very little on her part. I liked that I got to play such a subtle character in a film where every other character is just very aggressive, they're super caricatures. I really liked how she was understated. The main thing with Justine was part of what she needs to do is keep everyone calm and that her main objective is to blend in and that it's actually impossible for a women to do that when it's eight men with huge egos. You kind of become the center in a way that she's still trying to understand.

Well, was that part of the appeal, being the only women in this cast of men?

I mean, it's certainly flattering for a director to say, "You can express all of the female complexity in one person." But it's definitely not an appeal.


Yeah, that's not why I did it.

Well, I think it would be not a challenge but maybe a draw to be the feminine center in a movie where it's a bunch of guys with guns.

[Laughs] I guess! But if you go through my IMDb I think you'll be shocked to find that in almost every movie I've done I'm the only woman. I think this movie just really feels that way because it's so put on the character, and there's not a ton of setting. But that's part of the history of cinema, right? A bunch of dudes trying to get the one girl. So I love Ben and I know why. It's the same thing with "Kong" -- it's a certain period of time, there's a certain point of view and there's meaning behind the fact that there's one woman. So I don't mean to say that it's not good. But I also don't want to say that this conversation ends there. I would love to be in ensemble female movies and would love to work with more females. My story is not over.

Right now, you're in "Kong" at the same time as "Free Fire," and looking at what you have coming up there are really big movies and really small movies. What is the appeal of oscillating between those worlds?

It's switching genres; it's using different muscles. It's kind of like doing a bigger movie and then doing a smaller movie is sometimes I want to stay in a five-star hotel and other times I want to sleep in a tent under the stars. They both feed me in a different way, and I need different things at different times. I get a lot out of constantly staying on my toes and I don't really enjoy being too comfortable. There's something very calming about being on a bigger movie because you're very protected. The movie is never struggling. You're never worried about, if we don't make this day we're not going to get these scenes. But there's something that, since I've grown up doing independent films, that experience is very much a part of me. And I love being a part of that smaller knit group that's working together to get that ball to the line. I don't know. I just like all of it a lot. I don't want to get too far in any one direction.

Are you done with the movie you've directed?

I'm editing right now.

How was that experience?

It was really great. I loved every second of it. I hope it's good and people like it and I get to do it again.

You've worked with so many amazing directors. Have you called on any of them when you had questions making your own film?

I've wanted to direct movies since I wanted to act in movies, so I've always been a little sponge and observing the different directors that I've worked with and asked a lot of questions and I think that part of being a really good actor in its own way is being a little bit of a director. Because, sometimes, what changes the course of a scene is you and not the other actor you're playing off of. So learning how to position yourself to move scenes in a different direction and bring different colors out of actors was the first step in recognizing how directing is very subtle and interesting and like alchemy. So I feel like I've been leading up to my whole life. It's just not something I've been very boastful about talking about. I've been very much involved in wanting to do this and the editor of "Room" emailed me and said, "I always knew you'd direct I just didn't know you'd do it now." It just felt like it was right. It felt like if I didn't do it now then I'd never do it, I'd get too scared. I can do it while I'm still flexible.

And it's been everything you wanted it to be?

Yeah, I feel like I'm a better actor after doing it, I have a better understanding of the team aspect of making movies. I've always loved how everyone is a specialist in their field, and we all come together to create this piece of art. But after being on both sides of it I feel even stronger about creating a positive team effort aspect of this really is. I'm excited to purely act in something.

"Free Fire" is in theaters this Friday.