Henry Smart is on the run. Fleeing from his Irish Republican paymasters, the men for whom he committed murder and mayhem, he has left behind his wife, Miss O'Shea, in a Dublin jail, and his infant daughter. When he lands in America, it's 1924, and New York is the center of the universe. Henry, ever resourceful, a pearl gray fedora parked on his head, has a sandwich board and a hidden stash of hooch for the speakeasies of the Lower East Side. When he starts hiring kids to carry boards for him, he catches the attention of the mobsters who run the distrist. It is time to leave, for another, newer America.
In Chicago there is no past waiting to jump on Henry. Music is everywhere, in the streets, in nightclubs, on phonograph records: furious, wild, happy music played by a man with a trumpet and bleeding lips called Louis Armstrong. But Armstrong is a prisoner of his color, and the mob is in Chicago too: they own every stage - and they own the man up on the stage. Armstrong needs a man, a white man, and the man he chooses is Henry Smart.