March 1971. Backstage at the Empire Room of New York's Waldorf Astoria Hotel. Louis Armstrong, the greatest trumpet player in the world, sits in his dressing room trying to pull himself together to do one final show. Because as long as they clap, Louis will go out there and play. His mind wanders through the amazing journey of his life and his complex relationship with his manager, Joe Glaser. In a tour de force performance, one actor journeys into the mind and heart of an American musical genius and the man behind the legend.