Director Questlove's music documentary explores and reclaims the legacy of the 1969 Harlem Cultural Festival: a watershed six-week event of the civil rights movement. It shows unpublished footage of live performances at Mount Morris Park (now Marcus Garvey Park) featuring some of the most renowned artists who contributed their legacy to shape African American music and culture, such as Nina Simone, B.B. King, Sly and the Family Stone, Stevie Wonder, and Gladys Knight & the Pips, among others.