Hayley Atwell has been kept "in the dark" about the real identity of her 'Mission: Impossible' character.

The 41-year-old actress plays a professional thief named Grace in 'Mission: Impossible – Dead Reckoning Part One' - but director Christopher McQuarrie made a concerted effort to create an air of mystique around Hayley's on-screen character.

The London-born actress - who stars in the movie alongside Tom Cruise, Simon Pegg and Rebecca Ferguson - told Collider: "I asked McQ this and he just kind of looked at me. He gave me this look where he goes, 'Ask me no questions, I’ll tell you no lies.' I wish I knew, but it’s wise that they’re keeping me in the dark, as well, because it keeps me on my toes, too."

Meanwhile, Vanessa Kirby recently revealed that she relished the challenge of portraying Hayley's character in 'Mission: Impossible – Dead Reckoning Part One'.

The movie features a face-swap between Vanessa's black-market arms dealer Alanna Mitsopolis, aka the White Widow, and Hayley's character Grace.

She told Variety: "It was so much fun. It was the first time two women have got to do that.

“It was such an amazing gift - because I love Hayley - to channel her and get to play her for a bit, and to get to play somebody that was totally out of control. My character is usually so restrained and composed and in control; it was really, really fun to play someone a bit scrappier and a bit messier. I’m naturally more messy in real life, so I felt more at home in that sense."