After years at the helm of his world-renowned advertising agency Happy Dog, New Zealander Scott Walker quit his job and follow his dream of becoming a director.

The result is directorial debut The Frozen Ground, a drama based on real events in the 1980s surrounding Cindy Paulson’s escape from the clutches of serial killer Robert Hansen and her role in helping State Trooper Glenn Flothe track down the killer.

Nicolas Cage, John Cusack and Vanessa Hudgens star and Lionsgate will release The Frozen Ground on Aug 23.

Walker talks to Anthony Abraham about how he tracked down the real participants, secured the help of a veteran producer and took a calculated risk on the Alaskan winter.

How did you get into directing?

I grew up in New Zealand. When I was growing up, being a filmmaker in New Zealand was not really an option. The more realistic career path for creating something that you could put out there and people could experience was advertising. So I got into advertising and that lead me to London and Hong Kong and all over the world. I founded my agency [Happy Dog] and helped develop all the brand creative behind the global launch of Xbox.

I was doing film courses at the weekend and went home and told my wife I was going to shut down my agency and see if I could teach myself to write and direct.” She was like, “Fantastic!” My accountant was like, “You’re nuts.” And that’s how it started. I taught myself to write a script. I had met [producer] Mark Ordesky when he was at New Line. He had done Golden Compass and all the Lord Of The Rings [films], so there was kind of a New Zealand bridge there and a UK bridge.

When I called him up out of the blue to see if he’d give me five minutes of advice I told him I was struggling to write a script and wanted to write something that was small and manageable. He told me to write the greatest thing I could write without any limitations, something I believed in. That’s pretty much what I did and when I came back to him a couple of years later he liked it and that’s when he came on board to produce.

Did you have any preconceptions coming into your debut?

It’s like that saying, How do you eat an elephant? One mouthful at a time. I told myself to focus on the script, then go to one cast member at a time, then meet some financiers. I was very aware that if I thought too much about it and let it affect me I would start to over-think things and it would get away from me. I was very fortunate because of advertising. My last big job for my own agency was running PlayStation’s account in London – it’s like a $100m account. I kind of already had experience of working with big pieces of business and big teams in a creative industry, so I just tried to keep thinking of it in terms of not letting it get to me.

The  more I focused on the story and the real people that were involved, the greater the responsibility I felt for how to tell the story because of the tragic, horrific events and how many people they affected. That always kept me very grounded the whole way through. There were consequences for the film and people I wanted to make pure above all else. All of that stuff really helped it become more important than just me making a film.

What aspects of this piece of history fascinated you enough to want to make a film about it?

I had a court researcher, a journalistic researcher working on this trying to find me case files before I phoned the real cop [Glenn Flothe, portrayed by Cage] to see whether he was even interested in helping. If he wanted to help me then I’d follow the story and see where it took me. If he said no, I’d write a comedy or do something else and find another project. It was very important to me that this was told with their involvement and support.

I was interested in the drama behind this. I didn’t want to do this as a thriller-horror; rather as a drama. I always thought of this film more as I was writing it in terms of films like The Accused – much more of a drama. So we went to Alaska. When I originally spoke to Glenn Flothe he said he would want to meet me. I flew up to Alaska in February 2009 and we met for three hours over coffee. I said I wanted to tell the victims’ story, not glorify what Hansen did. I wanted to tell it with as much truth as I could and as much honour and respect to the people who were involved – both victims and officers and everyone else – and do it from that angle. He said, “I’ll help you and I’ll give you everything I’ve got.” He didn’t want his name to be used because he said he’d just done my job and didn’t see himself as a hero. He said if I had to give him any money to give it to a children’s’ charity or crisis center, which I did.

What an amazing man, like a hero in the true sense of the word. He’s now a very, very, very close friend and he’s seen the film and sent me an amazing email saying how pleased he was how I managed to stay true to our original conversation. The last thing he said to me was, “I’ll help you with anything you want, but the reality is from my perspective is that I’m not the hero, Cindy Paulson is the hero and you need to find her.”

He hadn’t spoken to her for 25 years at that point. After a while, I managed to track her down and she’d never spoken to anybody about it. She’d never seen a therapist, she’d never told her family about what happened. So I ended up talking to her and I went to where she lived at the time and interviewed her for about 50 hours over five days. We started from when she was born through to where she is now. Every night, she would go home and tell her husband everything she told me.

She said, “Look, if any of this ends up in a film, he needs to know about it in advance. He’s never been one to press me about this whole story because he knows what it means to me.” From my perspective it was an enormous week.

She sent me a beautiful letter afterwards saying she felt like a weight had been lifted. It was something about [her relationship with Flothe] that was really genuine. He really cared and nobody else did and that’s unfortunately too common. There are scenes in the film, like when Glenn talks about his sister dying – it’s a true story, and exactly the way I put it in the film. It was kind of coincidence about their real-life experience. I would go back to both of them about a lot of things in the script to get their guidance tonally and tastefully and say, “Do you mind if I put this in?” or “I want to shoot in this location, what do you think about that?” They’re the ones who mattered the most to me about the film.

That must be so rewarding.

It is. Everybody has a different opinion and takes things out of the films in different ways. Then you’re re-editing and people are giving you notes. At the same time you just want to keep it so that I could say, “Hand over my heart, this is what I set out to do. I want the victims to be remembered.”

When we got to the end, I wondered whether I should put the girls’ photos up there and have that be the end of the film kind of in remembrance of them and I asked everybody who was working on the film. I showed it to Lionsgate and they were like, “Wow, you’ve got to keep that on.” Then one of the sisters of one of the victims said, “I think it’s beautiful, can you please change the photo and call her this?” And they sent me a different photo because that’s how they remembered her. It was a bit more than just making a film, I guess. It became a great life journey and experience.

I remember when I first met Cindy, I actually took Glenn with me because he was testifying in a cold case in the same part of the state where she was going to visit because of a death in the family – just coincidentally on the same day. I asked him, “Would you come out and see her with me? I can pick you up from the courthouse and we can drive out together.” He said sure. As we left, there were tears, they hadn’t seen each other in 25 years. We drove away and he said, “I don’t know where this is going to go, but even if nothing happens you’ve done something for me, which is fulfil a dream of mine, to see her one more time and know she’s OK.” It was like the film was just wanting to be made, in a way.

How did the project come together financially?

Emmett/Furla – Randall Emmett and George Furla. It was one of those things – I met his wife and we didn’t really know what each other did. She asked me one day and I told her. She said her husband would probably love to meet me. So we met. I think he thought I was just another first-timer who wanted to make a movie and agreed to meet me because of his wife. Halfway through he was on the phone with CAA on a Saturday going, “Hang on – who is this guy sitting in front of me, do you know about this?” Five minutes later he had hung up the phone and said, “I’m financing this film.” He brought Lionsgate in and Voltage for international. That’s when it really kicked off.

When and where did you shoot?

We only had one window I wanted to shoot in Anchorage, Alaska, and that was in October [2011], the cusp of when there is no snow to when there’s snow. I wanted in the film the sense of no-snow to snow, and almost the whole film freezes over during the film. Everybody told me it was totally ridiculous and I said we should look at this statistically and thought this looked like a pretty good time to be going.

End of the second week Sunday morning, I had about 30 texts and emails from people saying, “Look outside.” Two feet of snow had fallen and it didn’t stop snowing. We had the largest super-storm to hit Alaska in 30 years in our last three weeks of shooting. So I got my wish, which was crazy. I shot the whole thing in 26 days. I had 225 scenes in 26 days to shoot, which is crazy. I didn’t realise really how crazy that was. From day one to the last day, we lost three-and-a-half hours of daylight. By the end, we were only having the sun come up at 10 in the morning and set at 4pm. We ended up backing everything to night shoots towards the end, with me moving scenes into nighttime from what was supposed to be a day scene.

Then we started hitting zero degrees – it became so cold. Everybody stuck to it, not one single moan or grumble. Everybody understood the film and the place we were in, the people around us. Most of our crew were Alaskan and everybody we met was like, “I knew someone who knew [serial Hansen. I grew up on the same street as him. I used to go to his bakery. My father went hunting with him” because it was such a tight-knit community and this was the biggest case.

What was the energy like with Cage and Cusack when you shot the interrogation scenes?

It’s about a six-page scene and I split it into two. I was going to do one scene and then we were going to break for lunch then come back and shoot the second half – the really big climactic eruption. We were in a closed room with two cameras in there. It was very claustrophobic. I was letting John and Nic have free rein as to where they could move. I told them, “Don’t worry about the cameras, the cameras will find you. I’ve got that covered, just go for it.” The last take they did before we were supposed to break for lunch; they went into the next three pages. And actually that last take, everybody had chills watching what they were doing. It was pretty full-on – there were literally chairs flying in the room. A lot of that is the take that I used.

We came back after lunch to do it more and more to get more coverage and their performances were just picking up. That was an amazing day. Those guys, I’d asked them to try and not have a reunion prior to shooting that day. They both really respected that and came into the room that day in character and didn’t even really say hi. They sat down and said, “Okay, let’s go.” Both of them are so phenomenal. I’d given them both direction based on the FBI’s initial direction to the cop – how cops interview, how the room was set up. With John I’d gone through the full transcript – like the size of a phonebook – of everything Hansen had said and FBI manuals based on his particular sub-category of serial killer-rapist so we knew where Hansen was coming from.

I said to them, “I think this is like a chess game.” I thought of it a bit like Frost/Nixon, that kind of drama and intensity of these two people. Both these guys just brought it. It was amazing. There are about six minutes more of that interview sequence that I had to take out. I was told to cut the film down. But that scene goes on and it’s great – I mean, some of the stuff John ended up doing was so subtle and hidden, so creepy.

What do you have lined up next?

There are about three or four different projects. There’s a lot I’m doing, but I’m back into writing and researching. I imagine I’ll probably do another true story next, but I want to do something that isn’t quite as intense and heavy; something with a bit more action.