"Ray Donovan," the Liev Schreiber-led Los Angeles series that Showtime premiered with record success last month (and has since renewed), has been pushed on the scope of its serious drama and the brooding qualities of its lead. But "Masters of Sex," the other new show the premium network is set to debut this year, is lighter and racier -- as the teasers below indicate. The period show stars Michael Sheen and Lizzy Caplan as Dr. William Masters and Virginia Johnson, pioneers of research into human sexual response. Like "Kinsey," "Hysteria" and other explorations of similar territory, it gets a boost out of the contrast between frank subject matter and stuffier era-appropriate social mores. The series premieres September 29, after the season three premiere of "Homeland."