As children, Ruth (Knightley), Kathy (Mulligan) and Tommy (Garfield), spend their childhood at the seemingly idyllic English boarding school of Hailsham, presided over by Headmistress Miss Lucy (Charlotte Rampling).
As they grow into young adults, they find that they have to come to terms with the strength of the love they feel for each other, while preparing themselves for the haunting reality that awaits them.