Hayley Atwell says working in 40 degrees below zero temperatures in the Arctic was just part of the job for “Mission: Impossible — The Final Reckoning,” but nothing prepared her for the moment a polar bear wandered onto the set.

“We were so far north that the Northern Lights were below us,” Atwell said. 

The set being interrupted by the presence of a polar bear remains one of her strongest memories from five years working on the franchise.

The British actress, who plays Grace in the latest installment hitting theaters Friday, underwent extensive training to work with sled dogs on the frozen sea. The extreme conditions were real, no green screen effects.

“We had to train to know what it was like, how to survive, how to work out there,” she said.

Atwell’s character represents a departure from typical action film roles for women. Rather than serving as a romantic interest, Grace develops what Atwell calls a “nuanced intimacy” with Tom Cruise‘s Ethan Hunt.

“The woman is not just the object of desire or not led with a romantic agenda,” Atwell said, “There’s intellectual stimulation between them, common cause that brings them together, something that feels sibling-like, maternal.”

Working alongside Cruise for five years has given Atwell insight into the actor’s off-camera persona. The two have become close, he even took her grandmother on a helicopter ride at sunset on Christmas Eve.

“For a man who is an aerobatic pilot, seeing him be so gentle and kind and patient with her and explaining how everything worked, that to me was like just a mark of a really decent guy,” she said.

To prepare for her role as a thief, Atwell practiced sleight-of-hand techniques, even successfully stealing items from Cruise during filming, including salt and pepper shakers, a watch, a necklace and gym socks.

“I’ve never been a thief before. So I needed to practice,” she said.

Atwell describes “The Final Reckoning” as “the culmination of all the movies that’s gone before” that “ties up plot points and characters that people have been watching for the last 30 years.” The film received a five-minute standing ovation at its debut in France.

Despite the film’s title suggesting the end, Atwell remained coy about whether this truly ends the franchise.

“I’m not the head of the studio. I’m just an actor for hire. I have no idea,” she said when pressed about potential sequels.

“Mission: Impossible — The Final Reckoning” is distributed by Paramount Pictures and opens in theaters nationwide Friday.