Taking on Andy Serkis’ Breathe after wrapping Season 1 of The Crown, Claire Foy was amazed by her director — making his feature helming debut — and his crew, who seemingly made the impossible possible with the production. “The film was put together, financed, and everything was sorted within six weeks. I don’t know how they did it — not for a period film, not for a film that requires aging of the actors, so much medical equipment, and things to get right,” Foy told Deadline’s Nancy Tartaglione recently at the The Contenders London event. “It was meant to happen, I feel like, and they somehow did it.”

Based on the true story of Robin and Diana Cavendish — the parents of producer Jonathan Cavendish — the film sees Robin fall terribly ill, paralyzed by polio, leaving Diana to take care of her young, ailing husband in a love story for all times.

“[Garfield] prepared for it more than you can possibly imagine, and in a weird way, that helped me. He would often email me with things and conversations he had. I didn’t feel like it was massively important for me to go and meet people who were on a respirator,” Foy explained, recalling her preparations for the project. “It was important for me to meet Diana, who pretty much is the expert in caring for someone who is on a respirator. It was very important for me to get the technical aspects of caring for someone like that right.”

Check out more of the conversation above.