London 1940. Ruth a young schoolteacher volunteers as an escort helping to evacuate children from war-torn Britain to Australia and New Zealand. On the voyage she forms an unexpected bond with nine-year-old Fergus - and with Bobby a fellow volunteer who initially infuriates Ruth with his laidback air yet somehow gets under her skin and throws her ordered life into chaos. Tragedy strikes on Ruth's return voyage when the RANGITANE is attacked by German raiders. As the ship goes down the surviving passengers are taken as prisoners of war aboard the German vessel. To the rest of the world they are missing presumed dead. Decades later in Auckland Hazel boards a plane to London eager to explore Europe. Sitting next to her is a man named Joe. On her lap is a treasured book from her grandfather Fergus. A book that will finally reveal Ruth's story.