Marie Vassiltchikov was born on 11 January 1917 to the family of Prince Hilarion Vassiltchikov, who was a member of the Russian parliament. After the Bolshevik Revolution, her family emigrated from Russia. Subsequently, Marie grew up in various European countries, including Germany, France and Lithuania, where she worked as a secretary at a British legation. From January 1940, Marie and her sister Tatiana, despite not being German citizens, started working at the German broadcasting service and then at the information department of the German Federal Foreign Office in Berlin. Here Marie maintained contact with members of German aristocracy, which her family had already established in the Weimar Republic.

Among them were Claus von Stauffenberg and Adam von Trott zu Solz, who was Marie’s boss. During this time, Vassiltchikov started writing a diary. It became a detailed documentation of the German resistance in Berlin and of the future participants of the 20 July plot in particular. The diary also reflected the discussion and views of the German aristocracy on war and Nazism. Another part of her diaries reflected her experiences in wartime Berlin and the Allied air raids, especially the bombing of the Berlin Zoo. In the last months of the war, she was evacuated to Vienna, where she worked as a nurse.

After the war, she married a US Army officer and moved to Paris, where they opened a small architectural firm. When her husband died, she moved to London, where she edited her diaries to prepare them for publishing. She also visited her native city of Leningrad a year and a half before her death. Marie Vassiltchikov died on 12 August 1978 in London.