In 1905, a sixteen-year-old Austrian boy falls in love with the music of his compatriot Franz Lehár when he attends the premiere of Lehár's operetta 'The Merry Widow'. The boy dreams of becoming an artist in Vienna, has no great interest in politics and shows no signs of anti-Semitism. His name is Adolf Hitler. Inspired by real events, 'Song of Buchenwald' vividly portrays Hitler's transformation into a murderous, racist fanatic, and Vienna's degeneration into a hotbed of extremism and hate, where Lehár's Jewish wife Sophie and his Jewish colleagues—including the great librettist Fritz Löhner-Beda—find themselves in grave and constant danger. Yet one fact remains unchanged: Hitler is still a great admirer of Lehár's music. Can Lehár use this to persuade Hitler to spare Sophie and his colleagues, or will his pleas fall on deaf ears?