Mary Lou Williams (1910-1981), an innovative and prolific jazz pianist, composer and arranger, created some of the most sophisticated big-band hits for Benny Goodman, Duke Ellington and other popular orchestras of the 1930s. From child prodigy and "Boogie-Woogie Queen" to groundbreaking composer and musical mentor to some of jazz's greatest musicians, Williams seemed to redefine herself with every passing decade. Away from the piano, she defied expectations - as a woman in a "man's world," as a black person in a whites-only society, and as a non-conforming creative genius in an image-driven industry. MARY LOU WILLIAMS: THE LADY WHO SWINGS THE BAND examines Williams' life and career, and her enduring legacy. In telling her story, the film follows the trajectory of jazz through the lens of a pioneering African-American female instrumentalist. The documentary unfolds through Williams' words - voiced by Oscar and Emmy nominee Alfre Woodard (12 Years a Slave, State of Affairs) - taken from unpublished manuscripts, oral histories and media interviews. Tony- and Screen Actors Guild-nominated actor Delroy Lindo (Malcolm X, Crooklyn, Get Shorty) voices Mary Lou Williams' husband John, while Independent Spirit Award-winning actor Wendell Pierce (Selma, The Wire) portrays bandleader Andy Kirk. Interviews with scholars, friends and fellow musicians - including Geri Allen, Carmen Lundy, Hank Jones, Billy Taylor, Terri Lyne Carrington, and Esperanza Spalding- place Williams' personal story within a larger context.