Charlotte Gray (2001) on Netflix

Charlotte, a young Scottish woman, who has studied in France, is living in London during World War II. Within weeks she both falls in love with a young pilot and is recruited by the Secret Service to act as a courier for the French Resistance. However her mission behind enemy lines becomes a personal mission to find her lover who has been shot down. Assigned to a Communist Resistance group she encounters acts of betrayal from sometimes unexpected sources, but meets the violence of war and her own disappointment with hope....