Masters of Sex Season 4 is a drama TV series directed by John Madden and starring Michael Sheen and Lizzy Caplan. The story of Masters of Sex Season 4 describes the lives of William Masters (Michael Sheen) and Virginia Johnson (Lizzy Caplan), the so-called "explorers of human sexuality" in the 1960s and their influence on popular culture at the time. It is said that it was because of the in-depth research of these two people on sex that the "sexual revolution" in Western society, especially in the United States, was triggered. Caitlin Fitzgerald plays the "third party" between the male and female protagonists-Libby Masters, the wife of the male protagonist Masters.