I heard John Wells say something really smart, many years ago. He said, "Assume your audience is really intelligent. Assume that they are really smart, and tell your story that way." So, for me, it's about never assuming that they will go away because they're not entertained.

Seattle is beautiful. You look at the sky and it's one of the most beautiful skies in the world, and then there's the Puget Sound, which will kill you, if you fall into it, but it's also beautiful. Seattle is a city of contradictions. It's the most liberal and most literate city in America, and it has Starbucks and [Bill] Gates, but it's also where the Green River killer hunted women and where the runaway population is just shocking when you walk the streets. Within the same city, there's darkness and light.

But, for the role of Sarah Linden, we saw everybody. Everybody wanted this role. Every female actor in town really wanted to play a real woman and be in this drama. It was incredible that all these women were coming in. And then, Mireille [Enos] walked in the door and she was reading the lines that I had written, and I saw her in that field. I was like, "Wow, she's the one."

It was a very, very intense and long casting process [for The Killing] because we really had to find the right people who could carry the weight of this story, who had the chops and who had the spirit, where they could bring in so much of their own selves to these characters. So, the casting process took many months.

Before I write anything, before I create any assumption in my mind about what it's like to be in that world, I go out there first. I'm very drawn to darkness and light, very drawn to cop drama, because there are very few places besides war and murder and a homicide investigation where you see the extremes of human nature - the darkest crevices and cracks in what people do to one another.

I am endlessly fascinated by this notion that everyone has a secret. Some of our secrets are tiny, small things, and some of them are huge. Given that reality of the human condition, that's what our characters will go through. There will be some things where you'll just be like, "What the hell! How the hell did that happen?"

Because we spent so much time in the writer's room, not even talking about where it goes, but just who the people are in our world, we could find all those unexpected moments and twists and turns that we didn't even see ourselves.