With his role opposite Keira Knightley, the Scottish actor solidifies his place as lead actor.

In this adaptation of the book, 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.

“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.

“It is a romantic tragedy in every sense, but at the same time, it is definitely not sentimental,” the actor says. “Instead of overly engaging your emotion, it endeavors to engage your intellect also. And [so] the actors couldn’t go too far, I think. I could have gone much, much further, because I could believe in their love, and I could believe in his hate.”

Director Joe Wright opted to depict the army’s retreat from and at Dunkirk as a single highly choreographed shot. This précis of the sorrow and the pity of war, says screenplay writer Christopher Hampton, was “a response to an economic constraint.” The Dunkirk section of the book contains much more military action, with thousands of refugees streaming north, columns of soldiers being attacked by German bombers, and descriptions of sorties, side battles, and retreating armies. But with a cap on the film’s budget, Wright decided to capture the horror of the Dunkirk aftermath on a single day’s shooting. The beach was transformed into a macabre phantasmagorical Hieronymus Bosch scene that tracks Robbie as he and two of his comrades wander through the mayhem of the charred remains of a seaside resort where cavalrymen execute their horses, soldiers destroy their vehicles, and shell-shocked men sing hymns as a burning world descends into madness.

“To choreograph,” McAvoy recalls, “it took a couple of weeks to get it all set up. Joe probably took about two days with the main actors and the crew and then one film day with the one thousand extras in the scene. [But] he didn’t panic. [Instead] he did something very bold and very brave and very audacious. He decided to rehearse all day and then shoot for an hour and a half, two hours at the end of the day. We got three and a half takes. Two and a half of them were rubbish and one of them was great. We didn’t know that one of them was great because at the end of that day the monitor failed so we couldn’t review our work.” With a wry smile he notes: “So Joe was very tense. And as much as he tried to, he wasn’t on good form that night.”

McAvoy expresses much admiration for Wright, who, despite having now made only two feature films, has gained a reputation as being a “visual director.” 

“I always feel that Joe understands how to tell stories,” McAvoy says. “He has more than one thing at his disposal with which to tell a story, and he realizes he can use all of them. And they are not just visual. They are not just audio. They are not just actors. It is not just set. There are a million things in a film he can use to tell a story.”

Wright conducted a three-week rehearsal period with the cast, allowing all the actors to meet each other even if they weren’t in scenes together. To get into character, McAvoy read the script as many times as possible before filming started but found the rehearsal period particularly invaluable.

“The acting process in this film wasn’t about just getting a bunch of British actors who could do stiff upper-lip accents and put them in costumes and let them go, because they all know what they are doing” McAvoy says. “It really was about getting a bunch of people together, putting them around a table for three weeks and galvanizing them… So it was collective experience, actually, which you don’t always get in films. Quite often it is a bit disparate: I’ve got my trailer, and you’ve got your trailer, and we’ll see each other when it happens. It was never like that in this.”

Research into the Second World War was encouraged. To capture the stylized look of the 1930s period, McAvoy says Wright “very boldly want[ed] us to go some way towards not only behaving like people in 1935, but acting like the actors of 1935.”

Aside from investigating acting methods from that era, voice warm-ups were a “big thing.”

“We were never allowed to be off-voice,” McAvoy recalls. “There was no whispering-acting going on unless one was dying. There was no dropping of energy [with one’s] lines. It was all quite theatrical techniques. It was about getting the energy to the other actors, who would then give it back to you so the energy builds in the scene. Especially when you have a very restricted and internalized form of acting, and when it might in some ways seem that there is not a lot going on, you need that energy to drive the scene. And of course with all that internalization of such huge emotions, when it does come out, it explodes.”

In the telling of the film, Cecelia and Robbie reunite. They meet for the first time in six years in a teashop scene, and when Briony appears at her sister’s doorstep, both Robbie and Cecelia confront her with the past.

“[These] were the two scenes that I responded to the most,” McAvoy says. “And they were the two scenes that were the hardest because they are the two scenes where the character and the actor must become the most vulnerable… Technically, other scenes were more difficult, but emotionally those were the hardest.”

While those scenes may have provided McAvoy with the greatest challenge as an actor, it is the steamy sex scene with costar Knightley is a turning point in the film. Not one to kiss and tell, McAvoy diplomatically sidesteps any description of the scene other then to explain the mechanics of it: “There was a lip that was part of the library…there was a little shelf that came out and her bum kind of sat on that. I lifted her up and then it was all on from there.”

And although he has described himself as a “non-alpha” male, McAvoy cements the perception of himself as a sexy leading man with this role.