Kristen Stewart Explains How She's Preparing to Play Princess Diana in 'Spencer'

• In the upcoming biopic, Spencer, Kristen Stewart will play Princess Diana during a three-day period in December 1991 when the royal made the decision to leave her husband, Prince Charles. 
• "It's a really meditative project," Stewart said of the film, adding that Diana's story is "very slippery" and "really emotionally-packed...for a lot of people."
• "This is a really kind of poetic, really internalized imagining of maybe the heaviest three days’ time before she does something as gnarly as leaving the royal family," Stewart said of her process preparing to play Diana. "I'm just sort of reading everything that I can and then forgetting it, because it's kind of a really internalized story."

Kristen Stewart is taking her role as Princess Diana very seriously.

The 30-year-old actress is set to play the iconic, late royal in the upcoming biopic Spencer, which will take place during three pivotal days in Diana's life. Specifically, the movie takes place in December 1991, when Diana was spending the Christmas holiday with the royal family at the Queen's Sandringham estate and contemplating the end of her marriage to Prince Charles.

With a premise like that, it's no surprise that Stewart describes the movie as "internalized" and she's preparing for the role with that in mind.

"It's a really meditative project," Stewart told Entertainment Tonight of the biopic. "There are so many perspectives of her and of her story... it's just not a black and white thing and it's a very slippery, really emotionally-packed story for a lot of people."

So how does one prepare to take on a nuanced, deeply emotional project about the internal thought process of one of modern history's most iconic figures? Lots of reading, followed by lots of forgetting, apparently.

"This is a really kind of poetic, really internalized imagining of maybe the heaviest three days’ time before she does something as gnarly as leaving the royal family," Stewart explained of how she's preparing for the part. "I'm just sort of reading everything that I can and then forgetting it, because it's kind of a really internalized story."

In a recent interview with Us Weekly, Robert Jobson, author of Prince Philip’s Century: The Extraordinary Life of the Duke of Edinburgh, predicted that the movie won't be well-received by the royal family.

"I think the most important thing is how well the actress can interpret the role. We’ll have to wait and see on that," Jobson explained. "As for the photographs of her, I thought she looked remarkably like the photograph of [Diana]. Having been someone who has met Diana and knew her fairly well, I thought it was uncanny, really. But we’ll just have to see. I think what’s more important is the authenticity of the portrayal, and we’ll have to see how that develops because my understanding is it’s going to be a good script and it’s going to be a good premise, but it might not necessarily have actually happened in the way they’re saying."

Spencer doesn't have a specific premiere date yet, but is expected to be released in the fall of 2021.