From PBS - Billie Jean King is the single most important female athlete of the 20th century, winner of 39 Grand Slam titles and a major force in changing and democratizing the cultural landscape. AMERICAN MASTERS looks back to the 12-year-old girl who played tennis on public courts, observed disparity and, as she soared athletically, never stopped trying to remedy inequality. Perhaps best remembered from "The Battle of the Sexes" match vs. Bobby Riggs on Sept. 20, 1973, her competitiveness on the court was matched by her efforts on behalf of women and the LGBT community, and her commitment to prove there is strength in diversity. King presents her own story, with perspective from Serena and Venus Williams, Hillary Clinton, Maria Sharapova, members of the Virginia Slims Circuit "Original 9" including Rosie Casals, Gloria Steinem, Chris Evert, Bobby Riggs' son Larry, family, friends, and many others. Through these interviews and archival footage, the film illustrates the life of a woman whose journey became not just a battle for personal glory but a sociopolitical battle for equality for all.