If you think Jamie Lannister's walking a tightrope between good and evil, just wait until you meet Nikolaj Coster-Waldau's new character

The "Game of Thrones" star's new film "Shot Caller" present an even more stark portrait of moral side-choosing. Coster-Waldau plays Jacob, an affluent stockbroker and family man responsible for a fatal drunk driving accident who in a sincere effort to make good accepts a sentencing that places him among the most hardened and deadly prison population, and his efforts to survive his incarceration lead to a startling transformation into Money, one of the prison gang's most ruthlessly effective members.

It's a harrowing performance from one of TV's most charismatic presences, and a role he relished for its all-too-human nuances. He's no fan of clear-cut good guy or bad guy roles, he tells Moviefone -- and that's why he's still not picking a side for Jamie, either.

Moviefone: What a dark and disturbing world you entered into.

Nicolaj Coster-Waldau: I know!

In your preparation, what was eye-opening about the world that you were going to depict?

There were quite a few moments of where I was like, to be honest, of disbelief. I love the script. I was blown away by the script by that whole world. But of course my question to the director Ric Roman Waugh was was like, "How real is this? Can it really be so?" Then doing the research, meeting the prisoners, going to prison, realizing that it's very authentic. It's a fictional tale, but it's very much based on real stories.

I met a guy who had been a shot caller, who was one of the exceptions to the rule. He left. He was out, but he had gone to prison as a 20-year-old. He was a non-violent offender, and he kind of went through that same thing, being dropped into the shark tank, refusing to be a victim, fighting back. Then joined the gang to survive. Doing the whole thing, learning how to be extremely violent, and that was an eye-opener. You always hear about these things, that prison is tough, and criminals are made in prison. But to actually find out that the reality is almost worse than what I imagined was really eye-opening and shocking.

Obviously, what I hope for is, first and foremost and most importantly, that people enjoy the movie, and entertain, and find it thrilling. Hopefully after you might think a little bit about this world. We're wasting so many resources with our prison system. It doesn't make sense that the wealthiest, most powerful country in the world incarcerates more people than any other country. That we lock so many people up, that we put so many non-violent offenders together with very violent offenders, and that's creating even more hardened criminals. It's just a waste of resources and a waste of lives.

Was there a particular scene or aspect of the film that took a lot of work on your part? That you really had to get yourself in the right place to pull it off?

One of the key moments in the journey is when he is asked to stab a guy for the first time, which is kind of a turning point in the life of Jacob. It's kind of when Jacob becomes Money, if you will. I kept trying to understand, first of all, I understood that he would do it because he was so afraid. I understood the whole fear. These guys are just in fear all the time, and spend so much energy trying to not show that fear.

But what actually happens in your mind when you stab someone for the first time -- I spoke to a guy who had done that. I asked him about it, and he was like,"First of all, you're more afraid than anything else." And then, when you finally do it, he said he felt, and the blood started flowing, he said he felt like a sense of empowerment and a sense of control that he hadn't had since he was thrown in prison.

But that was a tricky moment because I had to understand it on a very ... I can't explain it better than a basic level of the character. Then on top of that, of course there were the challenges of the physical aspect of getting ready to do the part was challenging, but it was also an easy thing. I knew I had to get to get to a certain size. I had to add some pounds of flesh, if you will. I think the biggest challenge was the psychological, trying to make the ends meet.

Did putting on the physical part -- the hair, the mustache, the tattoos, the muscles -- get you there easier?

Of course, yeah. Of course. Also, I think it was crucial for the audience as well, that you can see it. I think it wouldn't have worked if we hadn't done that. It has to be a tangible transformation. Also, that's what happens. You see these guys post-prison, they do do all that, because they put on the armor.

I asked this one guy about it. I asked the guy, "Are you all like white supremacists? What all these German Iron Cross -- what's all that?" He said, "No, we're not. We're gangsters. We're a gang. Yes, you can find a few guys who understand the ideology, but most of us, we're just gangsters. We put on this to put fear in you." And I said, "Well, it works."

But it also worked for the character. It worked for me. Because in the end, he is terrifying. The other guys respect him and fear him, which is important. You have to believe that. You have to believe that someone like The Beast or Jon Bernthal and those guys, they're very menacing when you see them. You have to understand and believe that they would fear this guy who, when he ends his prison, is a pretty shaken up man.You've been playing Jaime Lannister right on the razor's edge of good and bad. He does appalling things, and yet he still shows enough humanity that some of us still root for him.

Listen, the appalling things, that's also human. That what we have to remember, and that's what I love about "Shot Caller." We live in a world where we like to divide up into them and us, between nations, and between the color of your skin, and between gender, and we do between people -- when you're a criminal and you're put away in prison, then you become them, and you're no long one of us. I think we have to understand that them, they are us, and we are also them.

The key to these characters, like with Jaime Lannister, even though he does something horrific, like pushing a innocent kid out of a window, he's still a human being, and he does it because he had some reason. It doesn't make his action is horrific, but it's a very human thing to do, unfortunately.

As we see Jamie getting pulled in different directions now, are you rooting for him? Are you rooting for Jaime to have a redemption? Or are you rooting for him to go full evil?

I've never thought of him as being torn between the dark side or redemption. I hope that he finds a path that works for him, also when it comes to his messed up relationship to his sister. He's torn between this extreme sense of loyalty to his family and to his sister, and I think it's starting to get in the way of his judgment, to put it lightly.