While playing in a bar in St. Louis, jazz pianist Jigger Pine meets aspiring clarinetist Nickie Haroyen, who tries to convince him to put together a jazz band. After a drunk patron starts a fight, Nickie and Jigger, along with Jigger's drummer and bassist, are thrown in jail. They overhear a prisoner singing a blues song and are inspired to set out for New Orleans, where they hope to learn how to perfect an authentic bluesy sound. There they meet fast-talking trumpeter Leo and his wife, Character, who is a talented singer. Together, the quintet rides the rails, honing their technique in dive bars across the country.