Etsuko lives alone in rural England, trying to come to terms with the suicide of her daughter, Keiko. A visit from her other daughter Niki sends Etsuko retreating into the depths of her memory. She finds herself reliving one particular hot summer in Nagasaki, when she and her friends struggled to rebuild their lives after the horrors of the bomb and World War Two. As Etsuko examines her relationship with her daughters and struggles to cope with her guilt, the lines between the past and the present start to blur.