Sienna Guillory is best known for her role in series three of Luther, in which she played the detective's love interest. Prior to that, she appeared in The Buccanneers and The Virgin Queen, as well as playing the title role in American mini-series Helen of Troy. On the big screen, Guillory appeared opposite Colin Firth in Love Actually and has taken lead roles in sci-fi horror franchise Resident Evil and Eragon. In Fortitude, Sienna Guillory plays scientist Natalie Yelburton.

Sienna Guillory / Credit: Sky Atlantic
Sienna Guillory / Credit: Sky Atlantic

Can you describe your character and how she fits into the story of Fortitude?

Natalie? Hells bells. She's a sexually adventurous scientist. She maintains an emotional distance yet craves physical contact. Being a scientist means she doesn't take anyone's word for anything and has to find out things for herself. She's driven by this insatiable desire for knowledge and need to understand why things happen, so she's the tester of facts and bodies and people. She's a bit of an oddball, she wants everything on her own terms and she's really passionate about her work. I admire her sexual liberty and I believe she realises that women who can say yes to sex comfortably can also say no with confidence. Simon has written really strong characters, and it's nice to play a scientist. I know there are plenty of women on television playing scientists, but I don't think we can have enough. In 2012, only 13% of the UK's STEM workforce - STEM is Science, Technology, Engineering and Maths - were female, and I think diversity is important in any industry - diversity of thought leads to innovation. I think it's Natalie's openness to other possibilities that really helps get to the root of what's happening in Fortitude.

It sounds like you really connected with this character. Did you do much research to prepare for the role?

I read a lot and it was quite difficult, actually. There were lots of fiddly props and some ridiculous words, I was kind of juggling foetuses, Barbra Streisand and Iliad backwards. I read a lot about pathology, stem cell research, and PSAs in the environment and how they affect behaviour. I Googled a lot of stuff about the results of climate change and the way metals move through the food chain and how one would go about researching such things, so I had an understanding of what Natalie is talking about.

Your character does a lot of dissecting and other gruesome things. Did anything on set make you squeamish?

I loved it. It was like Halloween! It was really weird, dark stuff, some of the creepiest stuff I've ever experienced on a set - it made your skin crawl sometimes. The special effects people were amazing. I've done a lot of blood and gore before but this was on a completely different level.

Credit: Sky Atlantic
Credit: Sky Atlantic

There are a couple of love interests for Natalie along the way, but she likes to keep men at an arm's length, doesn't she?

Yes, absolutely. I don't want to reveal too much, but it's about maintaining an emotional distance because, essentially, she doesn't trust anyone. She likes to find things out for herself and she's comfortable with the physicality of discovery.

So how would you describe Fortitude as a whole?

It's bloody, beautiful and chilling. It's a sort of gloriously noir murder ensemble piece set in a tiny Scandinavian town in the Arctic Circle, and it's a town full of fairly odd personalities with their various accompanying personality disorders. We're like a bunch of naughty children, you know, running as far away as we possibly can and building a fort where we can do what we like, so we sort of create our own rules. It's a cold place full of warm people where dark things happen.

What was it about the series that appealed to you?

It was a combination of things. I loved working with Sam Miller on Luther, he's an incredible director, so I was really excited to work with him again. Simon's an excellent writer, he's very original, and the cast is just extraordinary. It's the most incredible cast you could wish to work with and everyone was lovely. Christopher Eccleston is the most amazing actor, and he'd go running for miles in his teeny-tiny shorts. Sofie Gråbøl is just incredible, an idol of mine, and Michael Gambon's a legend and the most brilliant storyteller. Richard Dormer is hilarious, and Stanley Tucci is wasted as an actor, he's a damn fine barman and makes the most brilliant martinis. Johnny Harris is the sweetest, most beautifully menacing man; we did a lot of boxing training together and I was terrified of getting punched. And then Luke, everyone loves Luke, he's wonderful. I had a bit of a game going with him where I tried to make him to say something negative, but he's just physically incapable of it, he sees the best in everything and everyone.

Obviously you all got on very well. Did that make it feel extra special while you were filming?

We all had a sense that something incredible was happening and we were all so intrigued to find out how the story would go and who would be doing what. Every time we got a new script, we were blown away scene by scene. All of the storylines are incredible. We really bonded in Iceland over a love of the script, love of the characters and the love of the place.

Do you share any similarities with Natalie?

We both have a massive love and respect for nature. I grew up in Norfolk, which obviously isn't the Arctic, but there's something about the wildness in both places that's incredibly liberating. I have a massive love for horses and she feels the same way about reindeer. I'm also a bit of a geek. I always want to be as prepared if not more prepared than I can ever be for something. Natalie doesn't leave anything to chance, she likes to be prepared as well. I don't know that she's particularly likeable, but I don't think I'm particularly likeable and it doesn't really bother me. I find Natalie really interesting, I like her strength and her convictions. She's a bit cooler than I am. Quite a lot cooler actually.

Did you have much downtime to explore the area while you were filming?

Iceland's extraordinarily beautiful and incredibly wild. It has such a tiny population and the people are so warm and trusting. The first time I flew in, I was sitting next to a teenage girl on the plane and it was dark and snowing when we landed. I was picked up at the airport and as we were driving away, there the girl was, walking down the road in the middle of nowhere with a little backpack on. I didn't like that so we stopped and offered her lift and she jumped in with us - so trusting. Kids here can barely play in the streets anymore, but in Iceland they have so much freedom, which I find really beautiful.

Why should Sky Atlantic viewers tune into Fortitude?

This is a rare piece of television. There is such ambition behind it and it's brilliant. It really grips you from the get-go.

FORTITUDE IS AVAILABLE ON BLU-RAY AND DVD ON 1ST JUNE