Atonement (2007)

On the hottest day of the summer of 1935, 13-year-old Briony Tallis sees her older sister Cecilia and their housekeeper's son Robbie Turner embrace. By the end of that day the lives of all three will have been changed forever. Robbie and Cecilia will have crossed a boundary they had never before dared to approach and will have become victims of the younger girl's scheming imagination, and Briony will have committed a dreadful crime, the guilt for which will colour her entire life.

Official website: http://www.atonementthemovie.co.uk/