Frail, disoriented, confused, forgetful: these are not the words you'd associate with Christopher Plummer. After all, the venerable, 85-year-old stage and screen actor seems as sharp as a tack.

Still, the star of the new drama Remember says he's felt something akin to the disorienting free fall of dementia.

"It has hit me a couple of times in the theatre," Plummer told the CBC's Peter Mansbridge in a recent interview.

Memory loss sits at the core of Plummer's latest movie Remember, a thriller by Atom Egoyan about a man suffering from dementia. With the help of a fellow Holocaust survivor, Plummer's character sets out on a revenge mission against the person responsible for the death of his family.

"I came on and I couldn't speak," Plummer said, describing an opening night in Banff. "I absolutely was paralyzed… I didn't seem to care whether I remembered [the lines] or not.

"I sat down onstage while the music was playing and I thought 'My God, this is the end of my career.'"

By the time the orchestra was done, however, he'd regained his footing, leaving the audience none the wiser if perhaps a little puzzled by the opening scene.

"They thought 'This strange entrance! The guy comes on and says absolutely bugger all and then goes and sits down,'" Plummer recalled with a chuckle.

Forgetting lines is a real possibility for most actors, even the acclaimed Plummer, whose decades on stage and screen have left him with a shelf of trophies, including a late-career Oscar. But he's never forgotten those disquieting moments on that Banff stage.

"Very frightening," he said. "There's always a moment when you think it's going to happen again."