Two people pass each other on the steep, thronged streets of Montmartre, Paris’ bohemian enclave, during the 1920s. One is a man in his fifties, sprucely dressed and sporting a bowler hat and a goatee; the other a teenager with a violin under his arm – he might even be busking with it. They probably don’t know each other, but each will leave his own distinctive mark on 20th century music.
