STACK talks silliness and scary mice with the stars and co-director of The Nutcracker and the Four Realms – Keira Knightley, Mackenzie Foy and Lasse Hallström.

Fifteen years ago, Keira Knightley featured in one of the most beloved Christmas movies of all time, Love Actually.

“I don’t often offer something for Christmas, but every fifteen years I’ll go, ‘Oh there’s another one.’ So Nutcracker is my Christmas season gift,” Knightley tells STACK when we meet in West Hollywood to discuss her role as the delicious Sugar Plum in Nutcracker and The Four Realms.

But Lasse Hallström and Joe Johnston’s frothy confection is not the Nutcracker of bygone years with images of a wooden toy soldier, holiday décor, dancing flowers and a little girl terrorised by furry mice.

E.T.A. Hoffmann’s original 1816 story, The Nutcracker and the Mouse King, inspired spectacular stage adaptations that have charmed audiences for generations, and now this epic big-screen adventure featuring Knightley, Helen Mirren and Morgan Freeman; introducing gorgeous Mackenzie Foy as the science-savvy young heroine, Clara.

“The story has changed a lot throughout the course of history,” says Hallström. “Alexandre Dumas’ version was less scary, and later became a ballet featuring music by Tchaikovsky. The ballet is unique with each staging, evolving within the minds of those creating it. We’ve done the same thing but we’re adding to the story.”

Growing up in the London suburbs, Knightley vividly recalls pilgrimages to see Nutcracker Christmas specials.

“The first time I saw it I was three years old and was completely terrified of the mice and hid under my seat. Second time, I didn’t really like the Sugar Plum Fairy. It was all about the Mouse King and I wanted to be the mice that I’d been terrified of three years before. My mum got me a sword and I got to play the Mouse King a lot, apparently. By time I saw it a third time, I was nine, and loved everything about it,” says the radiant actress, dressed today in an elegant Gucci dress.

Fast forward and Knightley, 33, has been wed five years to musician James Righton and now a mother herself to three-year-old daughter Edie.

“I still think my daughter is too young to see it. I think the mice would absolutely terrify her,” says the actress who is barely recognisable beneath her Sugar Plum make-up, adopting a girlish high-pitched voice for the role.

“I tried the voice out on a couple of six or seven year olds when I was playing in the sandpit with my daughter, and they all laughed. So I thought, well that’s the target audience. They all laughed, so that should be all right.

“Other than that, I asked myself: What else do we know about the Sugar Plum Fairy? She’s sugary and she’s sweet, so I wanted my voice to be a little bit sugary and sweet. I just made it up really.”

But, most of all, it was an opportunity for the Bend it Like Beckham and Pirates of the Caribbean star to have fun after a series of more dramatic roles in The Imitation Game, Everest and Colette.

“I really wanted to do this because it was a chance to just be very silly, whereas a lot of the work I do is quite serious and subtle. So, with this, I was like, we’ll banish subtlety and just be really, really silly. And my Sugar Plum is pretty silly, so I think I achieved that.”

While marking her first lead role with Nutcracker and The Four Realms, Foy is no stranger to film; just 11 when she landed her breakthrough role as Renesmee, the daughter of Bella and Edward in The Twilight Saga: Breaking Dawn – Parts I and II, going on to play the younger version of Jessica Chastain’s character in Interstellar as well as roles in The Conjuring and Wish You Well.

“I love that Clara is determined and she’s up for anything,” says Foy, 18, whose character is at the heart of the story. “But I also love that she’s a mechanic and loves science while at the same time she wears dresses.”

She hopes she can set an example of what it is to be a young woman today. “I honestly think women can be anything they want to be. If you want to like dresses, you can like dresses. If you want to like science, you can like science. So it’s cool to see the story adapted onto the screen but now being portrayed by a young girl.”

Working with Nutcracker’s veteran cast wasn’t too shabby either. “Being in a scene with Keira and finding the groove between her and Clara was really fun. There’s some really cute scenes where we have this really funny banter.”

If she’d like to enjoy the same careers as her co-stars, then she says, “For myself, I think it’s always important to remember who you are and to follow your heart and listen to it.”

The Nutcracker and the Four Realms is in cinemas on November 22.