On the hottest day of the summer of 1935, thirteen-year-old Briony Tallis sees her sister, Cecilia, strip off her clothes and plunge into the fountain in the garden of their country house. Watching her is Robbie Turner, her childhood friend who, like Cecilia, has recently come down from Cambridge. 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 not even imagined at its start, and will have become victims of the younger girl's imagination. Briony will have witnessed mysteries and committed a crime that creates in her a sense of guilt that will color her entire life.