Remember and Heart of a Dog compete for top prize in Venice Film Festival
Plummer plays Zev in the movie, who sneaks out one night on a quest to find the concentration camp guard - and to kill him with a Glock pistol.
Christopher Plummer plays an Auschwitz survivor searching for a former camp guard in a film that explores the themes of memory and undying anger.
In Canadian director Atom Egoyan's Remember, competing for the top prize at the Venice Film Festival, Plummer, 85, plays Zev, a dementia-stricken resident of a Jewish home for the aged in New York.
At the behest of wheelchair-bound resident Max (Martin Landau), and as a promise to his dead wife Ruth, Zev sneaks out one night on a quest to find the concentration camp guard - and to kill him with a Glock pistol.
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"It's the last time we can tell this story in the present tense. In 10 years it would have to be a period piece," Egoyan told Reuters in an interview, referring to the advanced age of the remaining Holocaust survivors.
"It's very important to understand that even though we all would love to live with the cliche that time heals wounds, and that there is the possibility of rapprochement, there are a lot of people who live with rage.
"There are a lot of people who are still as angry as though it was yesterday."
Plummer, whose most famous role was as Captain von Trapp in The Sound of Music (1965), was not in Venice for the premiere but told a news conference by video link that he'd been intrigued by the character of Zev, whose memory fades in and out.
In order to carry out his mission, Zev reads instructions in a letter given him by Max, who by telephone arranges everything from limousines to hotel rooms in the quest across America and in Canada to identify one of four people, all living under the same name, as the actual camp guard.
"It was not easy, let me tell you, because I'd never done anything like this in my life before. Although I've played a lot of different people, they've all had great confidence and great authority and some (were) even royal," Plummer said.
"So...I was dying to play an ordinary man, a simple, intelligent and educated man but who was very introverted, to say the least, and it was something very foreign to me but I was dying to accept the challenge."
German actor Heinz Lieven, who plays one of the four men Zev has been tasked by Max to track down, said it was important that the film was made, to help keep the memory of the Holocaust alive and to educate younger generations.
"When Hitler came to power I was four years old and when he was at his end (I was) 17...which means I know these times, the incredible murdering," Lieven said.
"Younger people have to learn, have to know it," he said.
The film won mixed reviews in the trade press, with Variety praising Plummer's performance but describing it as a "state-hopping Nazi-hunt mystery that puts a creditably sincere spin on material that is silly at best".
Laurie
Anderson riffs on death in Venice
Laurie Anderson has never been conventional, so it is no surprise her film Heart of a Dog touches on the loss of both her rat terrier Lolabelle and her husband Lou Reed.
The US musician and performance artist, whose work over the decades included the global pop hit O Superman and the post of artist in residence for the US space agency NASA, said animals and humans were kindred spirits in eastern religions.
Anderson, 68, told in an interview on Thursday that she did not make the film, which is competing for the top Venice Film Festival prize, as therapy for the loss of two important spirits in her life.
Instead, she hopes people who see it will learn to face death with open eyes.
Americans, she said, tend to deal with death "and war and a lot of other things just in the most remote way you can possibly think, the most hands-off way". By contrast the rock musician Reed had always been a "fierce" artist, Anderson said.
"I still learn things every day about what he did, people tell me what he said and what he did and I think about it," she said
"You can imagine if you've lost your partner how that is," she added. "Fill in the blanks."
She said Lolabelle, too, had shown the ability to learn and deal with change, as she became blind in the last few years of her life. Rather than have the dog put to sleep, as a veterinarian suggested, Anderson found a trainer who taught Lolabelle how to play a keyboard and paint, after a fashion.
Once, when Anderson was hiking with the dog in California, a hawk swooped down to attack Lolabelle but then backed off.
For the remainder of her life, Lolabelle was wary of being attacked from above, said Anderson, just as the Sept. 11, 2001 attacks forced New Yorkers to think about what might come from the sky.
"For New Yorkers certainly it has become something that is very attached to fear instead of freedom," she said.