Sienna Miller: 'The story of American Woman is every parent's nightmare'
After a string of supporting roles, Sienna Miller takes centre stage in American Woman, about the mother of a missing girl. She sits down with Laura Harding to discuss how the film affected her as a parent, what she looks for in her parts and shaking off the misconceptions
When most actors transform themselves for roles it involves heavy prosthetics or the incredible gaining or losing of weight.
They are unrecognisable under wigs, false noses or an extra 30lb.
But Sienna Miller does not need any of those things to completely disappear for her latest role, that of a single mother whose life is changed forever when her teenage daughter goes missing.
Set over 11 years in rural Pennsylvania, American Woman follows Deb Callahan as she is left to raise her young grandson and hope that one day she will discover what happened to his mother.
"I read it and I knew within 10 pages that I had to do it, I just fell in love with her," Miller says earnestly, as she leans forward in her chair in a London hotel room.
"I loved everything about the way that it was written and I loved that she begins as one woman and ends a different woman and you get to see somebody mature and earn respect as you go on.
"I had a really clear vision for it and it felt like a total gift."
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In fact it was the gift that 37-year-old Miller had been waiting for - a true leading role after supporting parts in prestige projects such as Foxcatcher, American Sniper, High-Rise and The Lost City Of Z.
"I've done a lot of films where I was a supporting part in really big, great films, but you're really focused on making an impact without that much time to do it and this felt like something I could map out in its entirety.
"It was just absorbing and all-encompassing because she was such a complete woman.
"It certainly was different to anything I had ever read and I think people are finally more focused on female-centric stories.
"It could have gone in a million different ways - it could have been a thriller, it could have been generic - but it was really in that 1970s way of film-making, a study of a woman and her life and everything happens through her perception of it, which you see all the time with men but I've certainly never had that opportunity as a woman."
She takes a pause as she sits back in her chair.
"I didn't feel unsatisfied with the work I had done, I felt like I had had opportunities to play really rich, diverse people, but I had never been in every scene of a film before," she adds.
"That meant I felt in charge of a story and in charge of how an entire thing was portrayed. I could map it out in a detailed way, how she should move in the first iteration of her to the second to the third.
"When the movie begins I felt like she should never sit still, she was just a simmering, bubbling ball of energy so a lot of it was handheld and I just wanted freedom to move around so I could hop up on a counter.
"She is just always moving to the point where it's quite jarring.
"And then the tragedy happens and there is sort of stunned slowdown, she's in a little bit of shock and by the end it's just more grounded and still.
"It was more work and I really love hard work."
But more work brought profound pain, as she immersed herself in the mind of a mother who loses her child (Miller herself is a mother to seven-year-old Marlowe, her daughter with actor Tom Sturridge).
"It was agony, because however much she moves away from that tragedy it can never be anywhere further than just below the surface," she admits.
"So, even in moments of humour, there is something behind it, so you have to really hold on to and sit in that space of the most unimaginable grief.
"There were moments where I really fell apart, but I had this crew and Jake Scott (the director) is a huge empath and this cast that were all there to help me through it.
"But there were moments where I remember being in my trailer and just breaking down because it's your nightmare, it's everybody's nightmare."
Miller took strength from her conversations with real-life people who have been through the same horrific ordeal as Deb, finding resolve in theirs.
"Many people I've spoken to have gone through that experience and there is this resilience to the human spirit that is astounding and it's a celebration of what you can get through as a human, which I think should be looked at and should be honoured," she says.
Her immediate response to the film's script indicates how intuitive all her choices have been in her career, which took off in earnest with her breakout roles in the 2004 films Alfie and Layer Cake.
"It tends to be that I read things and I intuitively either respond or don't," she says. "And I know really quickly and I can't articulate what that is, it's just a feeling.
"But I really am a fan of natural things, I don't want hammy dialogue or big showy action things, I like it to feel truthful.
"This was about the best thing that I had read, for me personally."
She is hopeful that it is indicative of better scripts for women across the board now.
"I think there is a change in Hollywood in general where you are not just going to be a wife anymore; I think you will get real backlash if you try to just put people in a dress in a corner. I think there is a shift, it's all moving towards a better place for women."
It might even show a different side of Miller, who has long been a tabloid fixation and perhaps not always given her due as a performer.
"I think there has been a huge perception about who I was and what I was potentially capable of and I hope that, with the body of work that I have accumulated in my 37 years, at this point that no-one can really condemn it.
"I love that I play all these different characters - I was just in this TV show with prosthetics on.
"I feel capable of a lot and I hope people appreciate that."
- American Woman is in cinemas now