James McAvoy in Atonement Courtesy of Focus Features

VIEW FILM STILLS: Atonement
READ MORE: Atonement review
VIEW PHOTOS: Atonement in Toronto
WATCH THE TRAILER

As the good faun Mr. Tumnus in The Chronicles of Narnia, James McAvoy melted the hearts of children everywhere. He then garnered the attention of critics as the good doctor whose principles are tested in The Last King of Scotland, a biopic about Ugandan dictator Idi Amin. Now, as Robbie Turner in the costume drama Atonement, the young Scotsman plays leading man to Keira Knightley in a sweeping film about lovers torn apart by misplaced emotion and war.

"For some reason we love watching people being crucified," says James McAvoy of his character's journey in Atonement. "We seem to find that an uplifting experience. And I think it is [when] you watch good people suffer that you can identify with them."

In this adaptation of the book by award-winning novelist Ian McEwan, McAvoy plays Robbie Turner, the son of a housekeeper who has grown up on the sprawling Tallis family estate in rural Surrey, England. Robbie is caught between classes. Courtesy of his mother's employer, he has obtained a Cambridge education. But while he is invited into the Tallis family circle on certain social occasions, he will never be included in the esteemed echelons of the British aristocracy.

Then on a sweltering summer's day in 1934, 13-year-old Briony Tallis (Saoirse Ronan) sees her sister Cecelia (Knightley) strip off her clothes and plunge into the garden fountain. Cecelia emerges from the water in a see-through camisole and Briony witnesses a sexually charged confrontation between her sister and Robbie. But Briony has long suppressed a childhood crush on Robbie and struggles to fathom her own emotions toward him. By the end of that day, the lives of all three are irreversibly altered. Cecelia and Robbie traverse a social taboo that forever determines their fates, and Briony witnesses a crime that she cannot fully comprehend or accurately recall. Her actions on that day shadow her for the rest of her life. By the time she fully grasps the magnitude of her mistake, war has swept up all those affected by her misguided judgment, impeding Briony from finding the right moment to atone for her error.

Robbie is released from prison, but not in pardon for a crime he did not commit; his freedom is granted on condition that he serve King and Country on the beaches of Dunkirk. Cecelia, meanwhile, cuts herself off from her sister and her family. Working as an emergency ward nurse, she waits for Robbie.

"I think Robbie and Cecelia represent one of the main stories we love to tell," McAvoy says in his strong Scottish burr, "and that is humanity crucified. It is not what the film is about. It is not what the book is about. But it is one of the stories in it."

McAvoy, who admits that he had not read the book before he was cast (but did so immediately afterwards), clearly has a soft spot for this character: "The wonderful thing about Robbie [is] he is completely noble. He is a real hero…I cared a lot about this character. I love this character quite deeply. It is a hard for me sometimes, because I want to believe that they are real, which sounds ridiculous. I understand that. It made it difficult, because it would be very easy to get carried away with the emotion of it all. And that would be wrong because I think it is a very romantic film.