S1, E1: It's 1975, and two tennis greats - Billie Jean King and Arthur Ashe - are aiming to win Wimbledon titles but also, in their own ways, to change the world for the better. Back in the late 60s, as the women's liberation movement becomes headline news, Billie Jean King takes up the gauntlet for women in sport. Having dominated the women's game for years, winning several Wimbledon Championships, King is spearheading the drive for equal prize money and equal treatment of women, whilst Ashe focuses his attention on racial equality on and off the court.