"Operation Finale" mainly concentrates on the relationship between Eichmann, who’s played by Ben Kingsley, and agent Peter Malkin, played by Oscar Isaac. (Metro Goldwyn Mayer Pictures)

How do you get a man to sign what is effectively his own death warrant?

In “Operation Finale,” a docudrama based on a 1960 Israeli operation, Mossad agents track down Nazi official Adolf Eichmann in Argentina, where he has been hiding out and living a quiet life. The plan is to bring him to Israel to stand trial for his role in orchestrating the deaths of millions of people in Nazi concentration camps.

The film mainly concentrates on the relationship between Eichmann, who’s played by Oscar winner Ben Kingsley (“Gandhi”), and agent Peter Malkin, played by Oscar Isaac (“Star Wars: The Last Jedi”). For various reasons, Malkin and his team cannot simply grab Eichmann and haul him off to Israel. Instead, Eichmann must, of his own free will, sign a document stating he’s willing to go. It’s Malkin’s job to get him to sign, which he does after engaging Eichmann in casual conversation for nine days.

What eventually cracks Eichmann, Isaac says, is an appeal to his intelligence and pride in his accomplishments during World War II.

“His weakness is that he’s got an ego. He wants to be treated like he used to be treated. That was kind of [Malkin’s] way in there,” Isaac says. “It’s not that [Eichmann] was pushed into [signing]; it’s just he’s craving that again.”

Facing Eichmann is also a way for Malkin — who lost a large number of relatives in the Holocaust, including his sister and her children — to confront the evil that nearly erased his family from the planet.

“For Peter, it’s like, ‘I don’t know if I’ll ever have a chance to talk to this f---ing guy, and so I’m taking it,’ ” Isaac says. “To sit next to him and to smoke a cigarette — that, for him, was the most courageous thing he could think of to do.”

Kingsley looks at his performance as Eichmann as fulfilling a promise he made to Holocaust survivor and writer Elie Wiesel, who died in 2016.

“I modestly said to him, the next time I walk onto a film set that is appropriate to your story, I will dedicate my performance to you,” Kingsley says. “The integrity, the energy, the propulsion, the commitment to getting the truth of Eichmann onto the screen for the sake of the survivors, for the sake of the 6 million — to honor them and Elie, I had no other choice but to paint a portrait of a man.”

That does not, Kingsley emphasizes, mean he had to find anything sympathetic in a person who committed and took pride in undeniably evil acts. “I have a canvas on which I will paint the portrait. [Then] I will put my brushes down, I will wipe the paint off my hands, I will leave the canvas there,” Kingsley says. “He never, ever, ever got into me.”

Even so, Kingsley had a mental message for Eichmann as he was “painting” him, expressing his intent to leave an indelible mark so no one forgets. “I said, ‘And when I’ve got you on canvas, I will nail you to the gates of Auschwitz.’ ”