The day that thirteen-year-old Briony Tallis (Saoirse Ronan) came across her older sister Cecilia (Keira Knightley) and her lover Robbie Turner (James McAvoy) making love in the library was a day that would have repercussions for all three of them. Briony misunderstands what has taken place between them and her reaction later tears the two lovers apart perhaps forever as war breaks out in Britain.—mel47