When Game of Thrones star Nikolaj Coster-Waldau first met Norwegian director and screenwriter Erik Poppe to discuss a role in A Thousand Times Good Night, a gripping drama about a war-zone photojournalist, it took the actor a few minutes to get the picture. Poppe didn’t want the hunky Dane to play the lead; he wanted him to play the husband of Juliette Binoche, who was already cast as the photojournalist whose profession wreaks havoc on the home front. The casting caught Coster-Waldau by surprise, but it didn’t diminish his enthusiasm for the film. We spoke to him from Europe.

Given the film’s sombre tone and heavy subject matter, what was the mood on the set?

There’s no question the tone of the movie affects the mood on set. Juliette Binoche plays the lead, of course, and she’s a very dedicated actress and very thorough. Before we started shooting we spent a lot of time talking, to get the back story straight. But, to be honest, we didn’t have much conversation after that until we got to the end. We met as characters, and we didn’t have a lot of laughs in our scenes. Having said that, I had a lot of fun with the crew. You have to. Everything is so serious with the script, you have to relax.

At the other end of the spectrum, your next film, Gods of Egypt, has Geoffrey Rush in the cast. Basically, he’s insane, right?

He cracks up all the time. He’s very funny. But on Gods of Egypt, I played a god and he played the sun god Ra. If you can’t laugh about that, I don’t think you have a sense of humour.

The subject of A Thousand Times Good Night is very topical, given the recent beheadings of captured war journalists by ISIS. But it’s also relevant to Erik Poppe, who used to be a war photographer himself. That the film is autobiographical, did that attract you to it?

Passion is so important in movie making and storytelling. And Eric had it. I met him in Belfast, where he told me about his story and about how the script was very much about his life experience. I thought that it would be cool, that I’d be playing a war photographer – a real hero. He told me no, I would be playing the husband. A woman would be playing the war photographer.

Which is a twist, right? We have this image of war photographers as single-male adrenalin junkies, not a woman with two young children and a husband at home.

Exactly. And that raises a lot of questions when you see the movie. If it had been a guy, you might just accept certain things. When it’s the wife and the mother, it brings up so many questions. What is a good wife? What is a good parent?

Getting back to what you said about a war photographer being a real hero, I would imagine most photojournalists wouldn’t describe themselves in that way.

It’s an honourable thing. But one of the things that I made a point of talking about is that I didn’t want to romanticize too much. We all have these images of these fearless journalists. And they really are amazing. But this film raises questions about what’s right and wrong. She goes out, and her photographs get the attention of the world, sometimes drawing attention to kids in conflict zones. But is it worth the price if her own kids are broken because of her career?

In the film, she talks about finding a way to finish what she’s doing, and that she can’t just walk away from it. Is this film a way for Erik, a former photojournalist, to find closure?

You should ask him. But there’s no question he’s wanted to make this movie ever since he stopped as a war photographer. It’s one chapter closed, for sure.