When it was time to return to the franchise with Mission: Impossible – Dead Reckoning Part One, writer-director Christopher McQuarrie knew just the leading lady to star opposite Tom Cruise’s Ethan Hunt. In an interview with Collider’s Steve Weintraub, Hayley Atwell reveals that her character, Grace, was actually a collaboration that was a long time coming with the filmmaker and that the experience throughout production helped shape her action-packed entry into the Impossible Mission Force (IMF) legacy.

Dead Reckoning pits Ethan Hunt against an entirely new beast threatening humanity as well as his own past. This penultimate entry reintroduces familiar characters, like Henry Czerny’s Eugene Kittridge, as well as new faces like Pom Klementieff, Shea Whigham, and Atwell’s Grace. During their one-on-one, Atwell discusses the intense training and collaborative process it took to find her character and how the script would change to better serve the story as they developed the role.

Atwell also discusses Cruise as a scene partner, drawing out Hunt’s vulnerabilities and whether she realized what kind of commitment she was joining when she first said yes to the IMF. To find out more about how her involvement with the Mission: Impossible franchise changed Atwell’s life, you can watch or read the full interview in the video or transcript below.

COLLIDER: So I really want to start with a sincere congratulations. This movie is awesome. It’s the fastest 2.5-hour movie I’ve seen in a long time. I want to specifically talk about the fact that sometimes when you’re cast, you can have a small role, and it’s still cool, but what was it like for you getting cast and then Tom [Cruise] and Chris [McQuarrie] are like, “Yeah, you have a massive role. You’re involved in all the action. Get ready?”

ATWELL: Yeah, it was a lot. For context, when I came in to do the screen test, McQ had seen me in a play 10 years previously, and he was like, “What you do on that stage, I want to bottle it and put it onto a screen and write a character for you, but I don’t know what that is yet.” We cut to 10 years later, and he calls me up and he says, “Will you come in and read with Tom? We’re thinking of creating the next installment of Mission: Impossible, looking for a new leading lady opposite him.”

There wasn’t a character that I had to fit into, there was just this brief of going, “We want to find the actress who loves this work ethic, who loves the process of it, who loves to collaborate and throw herself into every opportunity with all of these resources of working with these experts, as is possible. And from that, a character is going to emerge.” And so it was a sense that you can sort of, on a daily basis, write yourself into the story, or if you become back footed, or a bit fearful, or a bit kind of like, “Eh,” or you take your eye off the mark, you could also backtrack out of the movie. That’s how collaborative it felt. So I came in going, “We don’t know who this character is,” she didn’t have a name for a long time, “But I will try lots of different things, and we’re gonna see what lands, and we’re gonna see what the film wants. I’m gonna see what the camera wants and, ultimately, what the audience wants.” So, here you have Grace.

Image via Paramount

Also, the other thing about this franchise is Chris is so good at writing great female characters. Let’s talk about the car chase in Rome. It’s so incredible and unique because it adds humor that feels earned, not just forced to make people laugh. Talk a little bit about filming that sequence because you also shot during the day in Rome, and the streets were shut down. It’s crazy.

ATWELL: It’s so crazy. You’re absolutely right. You know, McQuarrie is an incredible writer. He really understands structure and pressure and how to put characters together in a situation that they shouldn’t be in or don’t want to be in, and that has inherent tension to it. And so the comedic elements to that are sort of comic relief in between those moments of how high the stakes are, but nothing that feels too, as you said, too pushed, too forced, too reached for. Every time we tried something that felt farcical or felt a little bit too cute, it didn’t work, and we could feel it, and we could change and pivot and do something else.

But a lot of the humor came out of the natural circumstance of Ethan Hunt being undermined by a Fiat 500. I mean, that in itself is so brilliant. The car became a character in and of itself, and so to have Grace, who’s an outsider, not knowing who Ethan Hunt is, watching a man instead of turning on the engine, turning on the windscreen wipers—she’s a bit worried for him. She’s also kind of worried for herself that she’s not with someone who really knows what they’re doing [laughs], and so there was an ease with finding the comedy between us, I think, that came out of the circumstances.

What I love about Tom is that he’s willing to look stupid on camera, and there’s a shot in that sequence where he’s just almost giving up, like, “I don’t understand!” Many actors would not give that shot, you know what I mean?

ATWELL: Completely. I’m so pleased you picked up on that because you could see that every day he leaves his ego and his pride at the door. He is able to see power for the sake of a great moment in the movie or something new that we haven’t seen him do as Ethan Hunt. And to watch him find the vulnerabilities and the slightly more idiosyncratic version of Ethan, who feels a little embarrassed or humiliated–and he really leaned into that—the funnier it becomes and the more we like him. He’s masterful at knowing what the audience wants.

Image via Paramount

One of the other things about taking this role—because you’re in both parts—is this has been filming for basically 20 years, and it’s going to continue filming through the beginning of next year. Again, I don’t know how much of a role you have in Part Two, but was there any hesitation in taking a role that would require years of your life? Maybe you didn’t know at the time, but talk a little bit about that aspect.

ATWELL: [Laughs] Yeah, we didn’t know. I think with something with the ambition that they had for this, it was kind of obvious to me that this probably would run over a little bit. The training alone, before we began shooting, was five months. You also get the sense that they’re not going to stop until it’s right. They are so dedicated to delivering a film for the audience that truly delights them and surprises them from the last installment. So, when you’re there, you understand why things take as long as they take, you understand the level of detail that goes into it from every department and also changes that they’re making on the day when they come up with a better idea. They go, “You know what? We thought that idea delivered, but actually, we’ve come up with something that’s far more interesting,” and that has been naturally born out of a sudden change in location or something that I did that suddenly went, “You know what? Let’s actually have her, in this moment, take a left instead of a right.”

I love working in that way because it feels very alive. If this had been a script that we shot to the book every single day, that didn’t change, that was the same, then that takes a different kind of level of patience. But just the sheer variety of what I was asked to do and had access to learning was so all-encompassing that it’s, far beyond the film, really changed my life.

Also, there are very few filmmakers who can do what Chris and Tom do without a script. It’s madness what they can pull off.

ATWELL: It’s unbelievable.

Mission: Impossible – Dead Reckoning Part One opens in theaters on July 12. Check out Collider’s red carpet interview with Tom Cruise below.