MASTERS OF SEX, an American period-drama series, has become a signature program for the premium cable channel Showtime. It tracks the real-life sexuality researchers William Masters and Virginia Johnson in the 1950s and early 1960s. Cable dramas typically use shorter seasons than their network counterparts; seasons of Masters of Sex run for twelve episodes instead of twenty or twenty-two. This shorter schedule enables cable shows to attract stars like Michael Sheen and Lizzy Caplan, who were previously best known for movie roles. The lack of broadcast limits on pay-cable stations also allows shows to tackle subjects like sexuality in a more frank and direct way than did many drama series of the past. Showtime Networks/Photofest