TORONTO — Perhaps the easiest thing about Marie-Josée Croze's challenging role in "The Diving Bell and the Butterfly" was landing the gig. A mere 30 minutes after her audition, director Julian Schnabel called Croze to offer her the part of Henriette Roi, the speech therapist who treats stroke victim Jean-Dominique Bauby.

Getting hired might have been simple, but to act out the true-life tale on screen, the French Canadian actress faced an arduous task. As Roi, she creates a method by which Bauby (Mathieu Amalric), who is completely paralyzed except for his left eyelid, is able to painstakingly blink out his memoir. That book was published in 1997, days before the former French Elle editor died at the age of 43.

Croze, a veteran of such difficult films as "Munich" and "The Barbarian Invasions" (for which she won best actress at Cannes), knew that without the right touch, Roi would have been nothing more than a two-dimensional foil for the struggling stroke patient.

"She thinks she knows how life is. She is supporting everyone. She does it with all her heart, but there's a rigidity in her," says the soft-spoken actress.

Through her contact with the indomitable "Jean-Do," as Bauby's nicknamed, Roi transforms from a dry, scientific thinker into a humbled human who is moved by her patient's struggles to enjoy her own life.

"I remember feeling the same way when we shot 'The Barbarian Invasions,'" says Croze. "Both films show you how people at the end of their lives want to recognize how important friendship is."

Croze learned this lesson herself when her own mother was hospitalized. "At first, I was completely sure that I couldn't cry in front of her — that I should smile and make jokes with her like, 'Be happy, you've got drugs in your veins and it's free morphine,'" she remembers.

But as Croze soon realized, her composure wasn't helping. "When I didn't cry she thought I didn't care about her," she says. "Sometimes people who are suffering want to see that emotion. They want to see that people are fragile."