How George Gershwin and DuBose Heyward's song Summertime became a standard around the world. The film tells the story of its first appearance in the 1935 opera Porgy and Bess, charts how it has been reinterpreted by artists including Billie Holiday, Janis Joplin, Mahalia Jackson, Miles Davis and Ella Fitzgerald, and explores the many meanings that have been derived from it through the decades. Narrated by Pauline Black