Courland is an entity that no longer exists. With the Gulf of Riga to the north, the Baltic to the west and Lithuania at its southern border, and now part of modern Latvia, the region was occupied by Nazi Germany and returned to Soviet Russia after the war, remaining largely inaccessible until 1991. It is now a nowhere land of wide skies and forests, deserted beaches, ruined castles and ex-KGB prisons. For years Jean-Paul Kauffmann has been irresistibly...