Society may, any day now, lose its grasp of the lessons of The Holocaust as those who witnessed it pass from the scene. But those few survivors left continue their mission, to remind us, to pursue justice, to “never forget.”

“Remember” is a “Memento” mystery about the long reach of that crime and tragedy, and old men who insist on playing their parts to the bitter end. And it’s a fine showcase for two of the cinemas Lions in Winter, with touching cameos for their age appropriate peers.

Zev Guttman (Christopher Plummer) has forgotten much. He wakes up each morning and calls out for his wife, Ruth. A nurse tells him she died a week ago.

“I’m sorry, who are you?”

He doesn’t recall that they lived in a nursing home. He forgot he was sitting shiva, but a star of David around his next is there to remind him of his Jewishness. He didn’t realize her funeral is today, a week after her death.

But his old friend Max Rosenbaum (Martin Landau) can provide some reminders. And Max is dead-set on Zev “doing what you promised. What you promised me, and Ruth.”

He’s written a letter, stuffed cash and a train ticket in it. Read the letter, follow the instructions, “cross them of as you complete each step.” Dementia or not, Zev, “It means ‘wolf’ in Hebrew,” has a mission.

And as this engaging, confused old men slips out, charming children and their parents on the train, buses and taxis he takes, no one takes advantage of him. They connect with his sweetness, his confusion. Some read a little of his letter. None see his tattoo, the number marked on his arm.

Max has sent Zev hunting Nazis.

Canadian director Atom Egoyan (“The Sweet Hereafter,” “Where the Truth Lies”) likes his mysteries and his big, melodramatic twists. Working from a Benjamin August script, he sends Zev on his odyssey, traveling through the West, from dumpy houses to nursing homes, looking for a Rudy Kulander — “the man who killed my family, killed BOTH our families” Max insists.

Max sends Zev to a gun shop, where the sweet old man has to ask the clerk to write out “how to use it” instructions on the Glock pistol he sells him. Whatever is left of Zev’s memory, Max is determined to use it. Max’s life, even in supervised care and confined to a wheelchair (with oxygen tank), is immersed in research, investigations. Several men changed their name to Rudy after World War II and slipped into America. One of them must be Otto, the guard who committed mass murder at Auschwitz. Zev will find him for Max.

Zev travels, wakes up every morning asking for Ruth, and somehow gets back to reading the letter, his “Memento” and memory jogger. And he stays on task.

Plummer is, of course, the perfect blend of sweet dotage and quiet, murderous purpose. He makes every encounter Zev has memorable. And he’s aided by his co-stars, potential Rudys in his search — the great Bruno Ganz (“Downfall”), Dean Norris as the cop son of a dead “Rudy,” the great Jurgen Prochnow (“Das Boot”).

Knowning Egoyan’s penchant for twists, you wonder where this short, quiet but tense movie is taking us. Is Max taking advantage of Zev? Is everyone who they say they are? How will Zev handle finding the real Rudy? Will the old Nazi give Zev the grace of reading the Glock instructions before shooting him?

The mystery, the great cast and the slow simmer of tension that Egoyan builds into “Remember” recommend it. The third act payoff won’t be to every taste. Egoyan is the Canadian Spike Lee in that regard.

But “Remember” packages a fascinating mystery into history’s most important subject, and lets the threat of violence hang over it even as the memory of the violence that set this odyssey in motion linger in our minds as these doddering old men carry out one last reminder and seek one last moment of justice.

 
MPAA Rating:R for a sequence of violence and language

Cast: Christopher Plummer, Martin Landau, Bruno Ganz, Jurgen Prochnow, Henry Czerny, Dean Norris
Credits: Directed by Atom Egoyan, script by Benjamin August. An A24 release.

Running time: 1:34