In 1935 13-year-old Briony lives with her wealthy family in their mansion in the country. Robbie Turner, son of the housekeeper, fell in love with Cecilia, Briony's elder sister who returns his feelings. Briony who likewise fancies Robbie is desperate and accuses Robbie of a crime he did not commit. The life of the three characters changes drastically when Robbie is arrested after Briony bearing false witness. All of her life she tries to seek forgiveness.