The 1973 tennis match between Bobby Riggs and Billie Jean King was one of those crazy American events, a zany and outlandish spectacle that was, at heart, not a joke at all. Even at the time, people knew that Riggs and King would be remembered forever for this match, which became a flash point in American culture and remains a weird emblem of its era. “Battle of the Sexes” tells the story of that match and of the events leading up to it.