Keira Knightley stars in “Atonement,” an adaptation of Ian McEwan’s novel of the same name. Joe Wright, director of the 2005 “Pride and Prejudice”, is the one that decided to take to the big screen the love story between Cecilia, played by Keira, and Robbie, interpreted by James McAvoy.

The story begins on a hot day of the summer of 1935, at the English country estate of the Tallis family. Leon (Patrick Kennedy), the oldest son, is making a visit and the household prepares for his arrival.

In the meantime, Cecilia, Leon’s younger sister, is preoccupied with her attraction towards the housekeeper’s son, Robbie, who seems to show the same amount of interest. He writes to her a letter which is intercepted by Cecilia's 13-year-old sister, Briony, in which he declares his affection for her. Briony catches the two in a compromising position and because of her age she is not able to understand what it means.

Because of her vivid imagination, Briony falsely accuses Robbie for a crime that he didn’t commit thus separating him from Cecilia.

The next scene is fast forwarded four years after this event and we find Robbie serving as soldier in the World War II, wondering in France during the Dunkirk evacuation. Cecilia and Briony, now played by Romola Garai, are both nurses. Briony understands now the damage she has caused to Robbie. She has estranged herself from her sister and wishes to patch up things with her and Robbie.

If you wish to see if Briony succeeds and if the two lovers reunite, you have to be 17 or above, as the movie was rated R.

Talking about her character Keira says: "I love characters who are essentially flawed. And when you meet Cecilia . . . she knows she's being horrible, but she just can't stop herself,” L.A. Times quotes.

She continues: “So you've got this brittle being who's on edge, a woman who's a bit like a pressure cooker about to explode. The fact she's redeemed by love, by the sacrifice she's made, was a really interesting arc to the character."

Director Joe Wright admitted that initially he wanted Keira for the role of Cecilia’s sister, Briony, at the age of 18, but after seeing her at the premiere of “Pride and Prejudice” in Toronto, in a Roland Moiouret dress, he changed his mind, and thought she was perfect for the role.

Keira confessed that for this role she dived in Ian McEwan’s novel and analyzed every detail that could give her an idea of Cecilia’ personality, from her addiction of nicotine, filled ashtrays, books half-read and cups with lipstick strains on them.”

“With me it's always about finding the images that make the behavior make sense," says Keira.