Sienna Miller has mastered the act of disappearing on screen. She’s hidden behind ornate period costumes (Casanova), raspy accents (Factory Girl) and prosthetics that render her virtually unrecognizable (The Loudest Voice). But as Sophie Whitehouse in Anatomy of a Scandal, Miller embraces a new kind of challenge: hiding in plain sight.

The six-part limited series created by David E. Kelley and Melissa James Gibson begins with a bombshell: Sophie’s perfect husband, James Whitehouse (Rupert Friend), a member of the British Tory cabinet and the prime minister’s best friend, is caught having an affair with his parliamentary researcher, Olivia Lytton (Naomi Scott). He tells his wife the eve before the story is about to break. As the consummate political wife, Sophie thinks she might be able to forgive the cheating. But when Olivia accuses James of rape, Sophie is confronted with hard revelations — and even more troubling memories — leading her to reevaluate the kind of man she’s spent the formative years of her life with and the kind of person she’s become. 

The role hits close to home for Miller, who has weathered her share of public scandals and the accompanying paparazzi attention. “The experience that Sophie has of a story about to break that you don’t want to come out, I’ve definitely had that way too many times in my life, and it’s a horrible feeling,” she tells Tudum.

But that was part of the appeal of playing Sophie — someone identifiable and relatable. “I was excited to play somebody English, which I very rarely do,” the actor, who was raised in London, says. “I also play quite extreme characters. I hide behind a lot of prosthetics or accents. To want to just sort of take all of that away is intimidating and also exciting.”

Miller glides into her first scene in Anatomy of a Scandal, sleek and glamorous in a white dress and gold heels — the kind of stylish, understated outfit she might be snapped wearing in her own life. With her glossy blonde hair and delicate accessories, she appears to have it all together — perfect spouse, perfect friends, perfect life. But it’s all just a different kind of mask. “I always saw [Sophie] as a kind of swan on the lake, whose feet underneath the water are going 10 to the dozen but having her keep that composure and that stoicism,” Miller says.

Miller’s performance translates that “swan on a lake” feeling with both physical and emotional restraint: a raised eyebrow as James recounts his seduction of an employee, a slight head tilt when he denies assault accusations. From the stands at his trial, Sophie holds this painful composure as her husband is confronted by prosecutor Kate Woodcroft (Michelle Dockery). And that, in itself, reveals more about her inner turmoil than any outburst. “What happens to you physically when your life really starts to unravel?” Miller says she asked herself. 

She and Friend even worked with a movement coach in rehearsals to be able to wordlessly convey a marriage in distress; as the series progresses, they become reverse mirror images of each other, turning to speak just as the other looks away and vice versa.  

“They made Rupert and I do each other’s scenes, play each other’s parts and study each other’s hands,” Miller says. “Of course, if you’ve been together since university, you know every inch of that person. It’s mortifying standing on your first day of work to look into somebody’s eyes and really study their eyes and how it feels to hold their hand. [But] it was really helpful because by the time we were on film, we were very comfortable; we had done all the embarrassing things and had gotten to know each other.”

In preparation for the role, Miller also read Sarah Vaughan’s 2018 novel, which inspired the series, and watched videos of politicians’ wives, taking note of details like how they stood as their husbands delivered their statements. But other aspects of her character’s life required no research at all. 

“In the first episode, when [James] sits Sophie down to tell her that he’s had this affair and the story is about to break, my heartbeat started to accelerate,” she says. “I could hear it on the monitor. It was going faster and faster, and [director] S.J. Clarkson actually isolated that sound and uses it throughout the show.” Revisiting those moments was rough, she admits, but also cathartic. “Getting to reinsert myself into a familiar situation with a much older perspective is interesting. It’s like psychological tourism.” 

Anatomy of a Scandal takes Sophie on a similar type of mental trip into the past. On screen, Clarkson blurs memory and reality, inserting adult Sophie into scenes with her younger self as she tries to figure out how she ended up where she did. “The journey that she goes on [is one] of self-discovery and questioning her own complicity,” Miller says. “Sophie is discovering, ‘My God, I probably helped enable this behavior in other people because I didn’t say no when I kind of wanted to.’”

Miller says she could identify with the kinds of doubts — and rethinking of the meaning of privilege and consent — that Sophie finds herself grappling with. In fact, they are part of why she took on the role in the first place. “I increasingly see parallels between what I’m curious about in my own psychology and what I end up making,” Miller says. 

“I think that women of my generation can really relate to that,” she continues. “We sort of let men behave the way they wanted to because we didn’t want to offend, and that is shifting now. I’m raising a daughter in a different world, and I’m galvanized and excited by that change.”

It’s a shift Miller sees reflected in her own life and career, even today. In December, she turned 40, a birthday once viewed as the dreaded expiration date for leading ladies. “I met Sharon Stone recently and she was like, ‘You’re so lucky that you’re turning 40 now because when I turned 40 that was it.’ You really had to fight to be seen,” Miller says. 

Miller’s experience is quite contrary to this. Opportunities are no longer as scarce for women who are past the ingenue phase of their career, and she’s embracing the milestone that marks an “exciting” new chapter in her work — one where she can pursue projects like Anatomy of a Scandal that challenge and thrill her. “I feel quite settled and clear in what I love and what I want to do and what I’m capable of. I’m not at war with myself. I have a pretty good sense of what my abilities and strengths are, the people I want to spend time with. That’s the best bit of getting older.”

“It doesn’t feel at all like doors are being shut,” she adds. “In fact, [it’s] the opposite.”