Atonement: Plot Summary

Chapter 1: Young Briony Tallis writes a play while fantasising about heroic tales, setting stage to her role as the imaginative and tragic protagonist.
Chapter 2: Briony’s older sister Cecilia and childhood friend Robbie share a heated erotic moment near the family fountain, observed surreptitiously by Briony.
Chapter 3: Robbie writes a sexually explicit note to Cecilia, intending it as a joke, but accidentally sends it to her via Briony.
Chapter 4: Briony reads the note, leading to her misconstruing Robbie’s intentions towards her sister.
Chapter 5: Robbie realises his mishap and attempts to retrieve the note from Briony — too late.
Chapter 6: At dinner, Briony’s twin cousins are reported missing, leading to a search in the dark.
Chapter 7: In the course of the search, Briony comes across her cousin Lola being sexually assaulted, believing the perpetrator is Robbie.
Chapter 8: Briony accuses Robbie of the assault, leading to his arrest, making a decision that changes all their lives.
Chapter 9: Four years later, we find Robbie serving in the military during World War II as a result of Briony’s false accusations.
Chapter 10: Cecilia, now a nurse, is unable to contact Robbie and learns about the horrors of war through hospital patients.
Chapter 11: Briony, now also a nurse, tries to reconcile with her past actions and contemplates making amends.
Chapter 12: Briony visits Cecilia, who refuses to forgive her and insists Briony confront the truth of her false accusation.
Chapter 13: Robbie returns from Dunkirk, and despite the odds, is reunited with Cecilia.
Chapter 14: Briony plans to confess her lie to authorities, but is dissuaded by a fear of the harm it might cause Robbie and Cecilia.
Chapter 15: Cecilia and Robbie live out their remaining days together before Robbie’s death in France and Cecilia’s in a bombing raid.
Chapter 16: An elderly Briony, now a successful novelist, reveals the entire story as her work, a fiction.
Chapter 17: Reflecting on her life, Briony explains her need to atone for her actions and reasons behind providing an alternate ending in her novel for Robbie and Cecilia, offering them a happiness they were denied in reality.