The film is remarkable for painting such an unsettling and complex world within its tiny scope. Focussed around an imprisoned group of Jewish forgers coerced into helping the Nazi war effort, it poses difficult questions and gives no pat answers back. This is a world away from the emotional notes of Schindler's List. Did Ruzowitzky worry about taking on such a sensitive project?
"I wanted to make a movie not for the generation involved, who we could accuse," Stefan replies enthusiastically. "We could do that. But I felt the movie should be for their grandchildren. That means it has to be accessible. It's important to tell this story in an accessible way, and that means it's got to be exciting, gripping, suspenseful."
But one has to be careful? "Of course. From the beginning, I knew I had to worry about these things. And I tried to generate thrills, but never from the question of 'will they survive?' That's why the film starts after the war, so that you know he'll survive."
Ruzowitzky's desire to let events speak for themselves extended down to the details. "For instance," he continues, "we only ever used score to illustrate characters, never situations. There's one moment, where one of the counterfeiters is revealed not to be a printer at all, and Salomon has to hide this, and Marius [the composer] said to me, 'Please, can I do something with the music here?' And I said, 'No, I don't think that would be right.'"
Most of the film's tension arises from the clash of personalities: the seemingly-friendly SS guard, Herzog, who runs the counterfeiting operation, and Adolf Burger, an idealistic inmate who sabotages the process at the risk of everyone's lives. Caught in-between is the protagonist, master forger Salomon Sorowitsch, played with steely-eyed resolve by Karl Markovics. How did he find the part?
"I like this character - he fulfils all my demands of a good character. He's not a hero. I've never been attracted by heroes because they don't exist. They're pure, and nature is not pure. I prefer these ambivalent characters." After a moment's more thought, Markovics adds, "This goes back to the questions of the film. There are no right answers. Truth isn't pure."
Karl - a modest and unassuming man in real life - is bashful about the research he undertook in preparation for the role. "Journalists like to hear there was a lot of preparation … Okay. One can make it like that. I read books, but not for this, but just for myself. But I came to a certain point when I realised my knowledge wasn't helping me get at my character. Salomon didn't know anything about politics. He didn't care about any of that, he only cares himself."
Particularly bold are the parallels that start to develop between Sorowitsch, determined to ensure the survival of him and his 'mates'; and Herzog, as he foresees the fall of Germany and tries to safe-guard his family. Isn't it an unusually sympathetic portrayal of an SS man? Stefan nods carefully.
"He was based on much research," he says, with heavy emphasis. "We wanted this man who was friendly - the real man he's based on, whose name was Kruger, he introduced things like the ping-pong table, and the operetta music while they're working - but he's also part of this murderous system. I wanted him to be a contemporary, modern character, a kind of young slick manager type. You know, the kind that destroys families and regions by closing down a factory, and they have these nice words for that. And he doesn't want to see what's really happening. He wants to pretend."
And it seems even inmates themselves were unsure. When two of the surviving counterfeiters, Burger included, came to visit the set, they began to argue over whether Kruger was a murderer, or whether he had saved all their lives. "Of course, he was probably both," the director remarks.
The complexities are never-ending, it seems, with every viewpoint contradicted by another. "We had a woman, a Czech who immigrated to the UK, who was Jewish and whose step-father was in Sachsenhausen," Ruzowitzky says. "And she knew the real Burger. And she was helping on the script, and I was afraid she would say we've made our SS guy far too sympathetic, but actually she said Burger was too sympathetic. Because she saw in Burger a typical Stalinist - someone who says 'I have the absolute truth, I'm right, and I don't care who dies for it or who has to suffer.'"
"There are no answers," Ruzowitzky concludes. "Throughout, I tried to balance these things. It was something I learnt from biographies of inmates, that the system made it impossible to do the right thing. People trying to do the right thing would cause even more pain and death. That was the whole idea, to have the inmates turn on and destroy each other while the German SS guards just watched."
"If you like the movie, it's natural you ask 'What would I have done in that situation?'" Markovics adds. "If you empathise it will go on in your mind."