Allenstein, East Prussia, 1939 - Charlotte von Datski's parents hold a glittering ball to celebrate her eighteenth birthday and to announce her engagement to a Prussian Count. But Hitler is about to plunge the world into war - and East Prussia will be wiped from the face of the map. Charlotte is forced to leave behind her beloved homeland and flee to England. By 1946, Charlotte finds herself in London with her young son, struggling to adapt to a new country and a new way of life. But she carries a secret that both strengthens and torments her - and when a book entitled One Last Summer is smuggled out of a Russian prison camp and becomes an instant international bestseller, that secret is revealed. The book tells of an affair between a Russian POW and a Prussian aristocrat. Years on, Charlotte's granddaughter, Laura, comes across material relating to these events and persuades her grandmother to embark on a journey into her past. As Charlotte recalls the one great love of her life, she finally faces the demons that have haunted her for over half a century.