The documentary “Game of Thrones: The Last Watch” took fans inside the Herculean effort to film the final season of the megahit HBO series.

Jeanie Finlay, director of “The Last Watch,” spoke with Variety about how she became involved with the documentary, how much access she was given on set, and how longtime series extra Andrew McClay stood out among a cast of hundreds of extras.

Read the full interview below.

Whose idea was this documentary?

Two years ago, an Irish producer I know called me and said, ‘HBO is going to call. Take the call.’ So I spoke to three guys from the HBO New York office who said they were interested in a documentary on the final season and how would I approach it. This is my eighth feature documentary, so I just talked about my practice and how I would go about it. A few weeks later, I got a call to go meet with David [Benioff] and Dan [Weiss], Bernadette Caulfield, and Carolyn Strauss in Los Angeles. I flew out from England and talked for a couple of hours about how I would do it.

My films are known for their intimacy and finding unconventional characters. I thought that trying to tell the story of 2,000 team members is just unfathomable. Then I thought about the way “Game of Thrones” is structured. It’s a big story in the larger world of Westeros but you learn it through key characters and focusing in on the personal. What I thought I need to do then is find the Seven Families, seven departments and then seven really great people and follow them through the final season.

How much access did you have?

I was given pretty much unfettered access. My main fear was that if there was a leak that it would come from me or my team. The documentary was also a secret. It was meant to be a surprise when it aired. So I didn’t tell anyone anything about what I was doing for two years. It was very overwhelming, trying to keep that secret. It’s very strange at first and then there’s all this relief. It meant that I could make the film without the pressure of fan expectations. I could really concentrate on doing the work. That’s a real luxury because the fanbase is both large and ardent *laughs*.

People have really fallen in love with Andrew McClay. What did you find interesting about him?

You see in real time in the film me finding out about Andrew McClay. I was really fascinated by the casting department because I thought they were really the unsung heroes. You have like 500-600 extras on set during those big filming days. When Rachel recommended Andrew, I thought, “OK, I’ll find him.” There were all these guys with big beards and extras jackets, so I learned the deep mythology, this idea that you could be a Stark but never a Bolton and you hate the Freys and all this. When I met Andrew, I just knew. Sometimes you just get so lost in filming when you’re following someone who’s got real charisma or exactly what you need. It’s like time slows down and you’re watching the film already. I just absolutely knew. As soon as I’d filmed him, I said, “I’ve found the heart of our film.”

What was it like watching them film the ending?

I could feel the energy moving as we got toward the end of production. It was really difficult because it’s not like you have one big explosion and that’s the last day. It’s not the end of school where everyone comes together then leaves. It’s a sad, long goodbye that was emotionally exhausting because people were leaving over two months because of the way filming was scheduled. I knew that Andy’s last day was going to be on the same day as Kit [Harington]. I knew that by interweaving Kit’s story with Andy’s story, we’d really feel what it was like to be the audience. Andrew was a stand in for the audience, because he’s the person walking around set getting excited about Dothraki swords and asking me if I know what’s going to happen. Of course I told him, “You don’t want to know!”