Swedish actress Rebecca Ferguson is going to become one of Hollywood's hottest new leading actress once "Mission: Impossible - Rogue Nation" hits cinemas this July 31.

The actress had to do a lot of physically daunting scenes for the film, and at 5 foot 7 inches, producers were sceptical if she could handle it. But the 31-year-old actress proved herself to be more than capable, and even impressed those who have seen the trailers with her "thigh killer move."

Ferguson plays Ilsa, a mysterious assassin in the new "Mission: Impossible" film who rescues Tom Cruise's Ethan Hunt from his captors.

She, Cruise, and director Christopher McQuarrie actually thought it was a good idea for Ilsa to have her own signature killer move in order to establish a powerful and commanding presence.

In the end, it was Wade Eastwood, the film's stunt co-ordinator, who actually came up with the killer thigh sequence. Given her size though, Ferguson needed a body double to perform the killer move.

"I'm a small girl, and these are big men, and it's so not expected that I would be able to kick ass with lethal force," she told The Daily Mail UK.

She actually caught the attention of Cruise and McQuarrie because of her BBC Sunday night drama The White Queen, which tackles England's War of the Roses. The series is based on Philippa Gregory's self-titled novel.

They called Ferguson while she was filming "The Red Tent" in Morocco, and within a few days, she got the part of Ilsa.

Ferguson then started a rigorous gym program in order to handle the physical demands of her role as Elsa.

"They checked my physique. They had to know whether I could run, because for the stunt work they have to know that you are capable of doing it without tearing muscle tissue," she said.

"It was six hours a day, six times a week - for six weeks. I forced myself to go to the gym. It was my mission," she added.

Ferguson's leading man and film director actually have the same interest in old films, and they even referenced a classic movie starlet in her role as Ilsa - Ingrid Bergman. Cruise and McQuarrie sent her old Hitchcock films to review such as "Notorious," as well as several of Bergman's films.

"Tom and Chris are walking cinema dictionaries. I'd have to go home and look up all the references they'd made," admitted Ferguson.