Hayley Atwell was proud of Mission: Impossible bruises: 'I've got proof of my battle scars!'

Before starting to shoot her role of a professional thief named Grace in the just-released Mission: Impossible – Dead Reckoning Part One, Hayley Atwell spent five months working with stunt coordinator Wade Eastwood and his fitness trainer wife Sam.

"The bruises here and there that I would get were so minor and yet I would be very proud of them," says the British actress, 41, who spoke with EW on Wednesday, ahead of the SAG strike. "I would be like, 'I've got proof of my battle scars!'"

Atwell explains that she not only embarked on an exercise program to prepare for her role in the seventh Mission: Impossible film, which once again finds Tom Cruise playing super spy Ethan Hunt, but also embarked on what she describes as a life-changing, sugar-free diet.

"It transformed my body in terms of my energy, my clarity of mind, and the natural by-products that come from living an incredibly healthy way and understanding about nutrition and rest and recovery and injury and prevention and mobility," Atwell says. "The first time I had sugar again, I had this sort of sugar hangover the next day and felt awful." Did a tiny, imaginary Tom Cruise appear on her shoulder to say, "Told you"?

"No, he would never rub it in," she says.

Mark Metcalfe/Getty Images Hayley Atwell

In the film, Cruise's Hunt forges an at first uneasy partnership with Atwell's character in an attempt to combat "the Entity," a new kind of artificial intelligence with essentially world-conquering powers. The actress is receiving rave reviews for her performance. (EW's Maureen Lee Lenker called Atwell "the real jewel in the crown of this ensemble.") But the opportunity to perform opposite Cruise on screen has been a long time coming. In fact, filmmaker Chris McQuarrie, who has directed all of the Mission: Impossible movies since 2015's Rogue Nation, first came close to casting the actress over a decade ago.

"Hayley is someone we have been talking to, and talking about, going all the way back to Jack Reacher," McQuarrie says, referring to the Cruise-starring 2012 action-thriller, which the filmmaker also directed. "She read for us for Jack Reacher, and she was somebody we were interested in for Rogue Nation. It took us a while to find just the right character, just the right opportunity for Hayley to really play to her strengths."

In the years after she auditioned for Reacher, Atwell became well known to MCU fans for playing the role of Peggy Carter in a slew of films and the Agent Carter TV series. The actress most recently portrayed an alternative universe Peggy in last year's Doctor Strange in the Multiverse of Madness. The movie featured the actress as a version of the character who has become the superhero Captain Carter but is killed with her own shield by Elizabeth Olsen's Scarlet Witch, to Atwell's disappointment.

"It was great to see her in that outfit, seemingly taking a more active role," Atwell says. "But it was a very underwhelming moment for her to say, 'I could do this all day,' and then get cut in half by a frisbee. Definitely don't think that set-up delivered what I would have loved to have seen for her."

Paramount Pictures Hayley Atwell and Tom Cruise in 'Mission: Impossible — Dead Reckoning, Part One'

The actress is much happier talking about the shoot for Mission: Impossible – Dead Reckoning Part One, despite its tough and frustrating nature. The COVID-19 outbreak delayed the production's start by six months, and caused Cruise and McQuarrie to pause proceedings on several occasions, extending an already lengthy shooting schedule. "I think Hayley might have been on this movie for well over 100 days before she had her first dialogue scene," McQuarrie says.

A hundred days? What was the actress doing during that time? "Fighting, a lot of the stunt work, a lot of the running through the streets in Venice, a lot of the work in Rome," she says. "The big dialogue scenes, they came later on, once we had established the physicality of the character in all those bigger set pieces. Then we went, 'Okay, we've got to fill this in with some actual storytelling here. Let's work that out.'"

Much of "the work in Rome" to which Atwell refers involved shooting a car chase which found Grace and Ethan driving through the streets in a Fiat 500 while handcuffed together. In the finished film, Hunt almost immediately crashes that car after the pair get in the vehicle, a moment which, Atwell reveals, was not part of the day's shooting schedule.

"We nicknamed the car Trixie, because she had a life of her own," the actress says. "It wasn't planned that Trixie crashes immediately when we set off in her, but we did by accident, and it ended up in the film. It's such a great comedic moment. I mean, how lovely to see Ethan Hunt back-footed and undermined by a little yellow cupcake car."

Paramount Pictures and Skydance Tom Cruise and Hayley Atwell in 'Mission: Impossible – Dead Reckoning Part One'

Despite such moments, and Cruise's daredevil reputation, Atwell insists that her costar was always concerned about her safety on set and that she was having a good time.

"He wants to make sure that anyone that he's working with in those high-stakes environments that he's steering — literally and metaphorically — are capable but also safe and actually enjoying it," she says. "That's one thing he said about the training: when you find the style that you like, you'll be able to get more advanced in it, because you physically enjoy doing it."

Does Atwell think that the now-61-year-old Cruise will continue making these movies until he's, say, 150? "Oh, I don't doubt it for a moment," the actress says. "He loves it. He's an extrovert. He gets energy from being with people and making movies. His whole life is committed to this."

Paramount Pictures and Skydance Hayley Atwell and Tom Cruise in 'Mission: Impossible – Dead Reckoning Part One'

Cruise will, of course, return for at least one more Ethan Hunt adventure, Mission: Impossible – Dead Reckoning Part Two, which is set for release next June. McQuarrie and his cast had shot a chunk of the movie before breaking to embark on the publicity tour for Part One, but Atwell claims she is unable to tease the second half of the yarn.

"I can't, because I don't know what happens," she says. "So much of 7, we weren't following a set script. We were finding things in the moment and then seeing what the scene owed in terms of the plot and the exposition and the character dynamic. That's their process. It's a very unique one that clearly works for Tom and McQ because of what they've been able to deliver. What's great for me as an actor is everything is sort of up for grabs in terms of what happens next."

Mission: Impossible – Dead Reckoning Part One is now screening in theaters.

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