Atonement is a historical drama film based on the novel of the same name by Ian McEwan. Set in England before and during World War II, the story revolves around the lives of three characters: Briony Tallis, her older sister Cecilia Tallis, and Cecilia's lover Robbie Turner.
Briony, an aspiring writer with a vivid imagination, witnesses a sexual encounter between Cecilia and Robbie, which she misinterprets as an assault. Later on, she discovers a letter written by Robbie to Cecilia, which she reads and takes as evidence of his guilt. Driven by her desire to protect her sister, Briony falsely accuses Robbie of raping a young girl, resulting in his imprisonment and separation from Cecilia.
The film then follows the consequences of Briony's actions as they play out over the next few years, as the country is plunged into World War II. Cecilia enlists as a nurse, while Robbie is conscripted and sent to fight in France. Meanwhile, Briony is wracked with guilt over her false accusation and becomes a nurse as well, hoping to redeem herself and make amends for what she has done.
As the war rages on, the lives of all three characters are forever changed by the events of that day, as well as by the choices they each make in the face of adversity. Atonement is a powerful and moving story about love, forgiveness, and the consequences of one's actions.