“She’s such a big personality. She’s kinda lethal,” Blunt said. “She did not conform to the ‘50s housewife ideal. We love a nonconformist. And she was such a confidant for him and fiery and smart and troubled. Not an easy person. So I guess I saw her because she was a challenging person; it was a great challenge for me to take her on as a character.”

Kitty Oppenheimer
Emily Blunt

Katherine “Kitty” Oppenheimer, played by Emily Blunt, was a biologist, a botanist, and had married three times before she met Oppenheimer at a garden party in San Francisco. They married and had two children, Peter and Toni. During the Los Alamos years, Kitty struggled with dissatisfaction with motherhood, loneliness and addiction.

Blunt was intrigued by Kitty’s rejection of social convention or expectation. “Kitty is a character who doesn’t do small talk; she only does big talk,” Blunt says. “She’s complicated, volatile, bewitching all at once. What I really was drawn to with her is that idea of a woman who refused to conform to the sort of feminine ideal of the time, why you need to get married and have children and support your man and that’s your job and that’s all you’re allowed. She just had this defiance against the system that felt so modern. I mean, Oppenheimer’s her fourth husband, and she’s, like, 29 when she meets him! I think she just wanted to blaze through life to the beat of her own drum. But I do feel that in Robert Oppenheimer she met her intellectual equal. There was genuine respect there. She was such a confidante for him and was his main ally when it came to making big decisions. He leaned on her heavily and her opinion was of paramount importance to him. She herself was a scientist, and she is that prime example of a woman of that time with a brilliant brain that kind of went to waste at the ironing board, and she suffered for it. Yet she believed in Robert, worshipped him, supported him, and was his biggest champion.”

While Blunt dug deep into American Prometheus to find insight into Kitty, she says Christopher Nolan’s script, and his directing style, was all she needed to find the character. “Chris wrote an extraordinary character for me to dive into,” Blunt says. “Kitty exploded off the page to me; there was something monumental about her as a person. Chris gives you a lot of freedom, as a director, to explore the vulnerabilities of a character. If you see someone who is laced with a sort of volatility, or if she’s aggressive or she’s tough, I’m always looking for what’s underneath that, where’s it coming from, and how many things can you play in this one moment so it’s not just about anger. It’s about hurt, it’s about humiliation, it’s about exposure. All those things were there for me to find, and there was the creative freedom on the day to explore them.”

Blunt says that chemistry came easy for her and Cillian Murphy, as the two actors worked together not too long ago in A Quiet Place Part II, in which their characters developed a close bond and battled demons of a different sort. “This was my second movie with Cillian, and because we’d worked together, we have an ease and a trust with each other,” Blunt says. “It was so effortless to leap into playing a married couple who are so intertwined and such kindred spirits. To be on the other side of him in a scene, someone who has no ego, no agenda, who just wants to create something good and true with you, it was an amazing experience.”