This new documentary traces the incredible life of the single most important female athlete of the 20th century as her 70th birthday nears. American Masters looks back to the 12-year-old Long Beach, California, girl who played tennis on public courts, observed disparity and, as she soared athletically, never stopped trying to remedy inequality. During her professional tennis career, King won 39 Grand Slam titles, helped form the Virginia Slims Series (pre-cursor to WTA Tour), founded the Women's Sports Foundation and Women's Sports magazine, and co-founded World TeamTennis (WTT). Her competitiveness on the circuit was matched by her efforts on behalf of women and the LGBT community, and her commitment to prove there is strength in diversity. 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.