Vanessa Kirby says filming Mission: Impossible — Fallout was 'nearly the death' of her

She may live in her sister's shadow as Princess Margaret on Netflix's The Crown, but Vanessa Kirby stands squarely in the spotlight in Mission: Impossible — Fallout.

In the Tom Cruise-starring franchise's sixth film directed by Christopher McQuarrie, Kirby plays a pivotal role as a woman nicknamed the "White Widow," whom Ethan Hunt (Cruise) and his CIA counterpart August Walker (Henry Cavill) must find in order to complete, well, a mission. But while Kirby was comfortable slipping into her slippery character's skin, the stunts were another matter—especially when she had to go toe-to-toe with the notoriously stunt-happy Cruise.

Below, the actress talks joining the franchise in her first role after leaving The Crown and what fans can expect from the film.

ENTERTAINMENT WEEKLY: Why choose to join Mission: Impossible of all things post-The Crown?

VANESSA KIRBY: It's mad, I know! Of all things after The Crown! It couldn't be more different. We were filming the second season of The Crown and going to do some shooting days in London, and then moving on a Eurostar to film night shoots in Paris and then back to film The Crown. Really, it was nearly the death, the death of me.

I think it was because these movies in particular, if you look at the ensembles that have been in all of them over the years, you've got Philip Seymour Hoffman, Vanessa Redgrave, Thandie Newton, and Kristin Scott Thomas. You've just got all these amazing actors, and that was really exciting, to join the ensembles in that way. I hadn't done a movie like this before, I haven't really done stunts before, so it was hugely eye-opening.

Tell me more about the stunts. You did some yourself?

Yes, I did! A few. It was really amazing having Tom's guidance and watching him do all the choreography. I remember there was one sequence where I was like, "Oh my God, I'm literally working with a master." I didn't feel like I was in some green-screen CGI action movie.

What is it like working opposite Tom? Henry said Tom makes everyone feel like they should push themselves harder. Did you feel the same way?

Yeah, definitely! You have to meet him at his level, otherwise… [Laughs] You really, really have to step up, to be enthusiastic and on it and utterly professional. It's quite amazing to see him so disciplined and everybody so disciplined. I'd heard that about him but to actually do it was really true. Watching him taught me loads about discipline.

And I mean that literally; Tom does everything. I didn't really think he did until actually seeing him in person doing it all! And that is quite amazing — I don't know any other human being on the planet that does that to the extent that he does. You can talk about it and say, "Oh, you know, Tom Cruise does his own stunts," but to actually see a human being do the things that he does, it's just next-level, really. It's like a dance, like an extremely accomplished dancer that's also slightly putting his body at risk. I mean, there's his poor foot!

How did you prepare for your set pieces opposite him? I hope you weren't as injury-prone.

Basically, I went on quite a strict training regimen—we all did. The trainer took me on a run in Paris around a park, and I was literally wheezing at that. Puffing. I was so slow, I was crawling by the end. [Laughs] It was amazing. It was so different, and being challenged in that way is really great. You basically had to be able to keep up with Tom at his level.

So tell us about the White Widow. How does she fit into this picture?

She's a very, very high-level underground con artist who has links and networks all over Europe, and you're unsure as to which side she's on… I don't know [exactly] what it's gonna be, because I haven't seen the film, and there are so many stories to tell. I remember Simon Pegg talking about how his character emerged throughout the films, and that he never knows quite how Benji is going to be this time around. I have seen a little bit—I went and hung out with Chris in editing—and it's definitely about using conscience in ways it hasn't been before, and that is exciting. It feels very, very different from all the others—more real, more immediate, and more dangerous. It's like none of the others.

How did you prepare before stepping into the franchise? I read that you'd binged all of the films in one night?

Yeah, I watched them all in one night before meeting Tom! My poor boyfriend was lying next to me, and the theme tune was going through his dreams all night 'cause I just sat there watching them all. And then I went in to meet Tom and Chris, and of course it didn't even come up in conversation.

Just to wrap up, anything else you want to add?

[Mission: Impossible—Fallout] is not going to be what you expect. That's what I said to Chris and the editor, "This was so unpredictable and unexpected." But that's what makes it so exciting—I really mean it when I say it's not like the others. It's a whole new level of danger and it's incredibly emotional, which you don't really expect in Mission or action movies per se. That's the sense I got from it.

Mission: Impossible—Fallout hits theaters on July 27.