Maisie Williams has described the shoot for her upcoming TV show, The New Look, as "relentless".

The New Look, an upcoming Apple TV+ series, follows famed French designer Christian Dior as he creates a new fashion line in Paris after World War II.

Williams, who portrays his sister Catherine, a heroine of the French Resistance, admitted to Harper's Bazaar that the shoot was all-consuming.

"It was a long job, and it was amazing; my whole life moved to Paris. It was hard work, but it was such an honour to do this part, and it became all-consuming," the Game of Thrones star said. "This was a role that required an extraordinary amount of research and care - and it really hit me, bringing that wartime period back to the streets of Paris; like I could acknowledge the weight of it in a way that I hadn't before."

The actress reflected on the "relentless" process of "doing take after take", admitting, "It really breaks down your character in a way. It's not for everyone, but for me, I like to get lost in a role, and keep on pushing until we complete a scene."

As part of her preparation, the 26-year-old lost 26 pounds (12 kilograms) to achieve Catherine's emaciated figure, leaving her unable to sleep through the night.

"(This part) took over what I'm eating and how I'm moving and sleeping and thinking..." she recalled.

The New Look, starring Ben Mendelsohn as Christian Dior, debuts on Apple TV+ on Wednesday.