In May 1941, Gertrude van Tijn arrived in Lisbon on a mission of mercy from German-occupied Amsterdam. She came with Nazi approval to the capital of neutral Portugal to negotiate the departure from Hitler's Europe of thousands of German and Dutch Jews. Was this middle-aged Jewish woman, burdened with such a terrible responsibility, merely a pawn of the Nazis, or was her journey a genuine opportunity to save large numbers of Jews from the gas chambers?...