Niecy Nash and Betty Gilpin will be guest stars on the fourth season of Showtime Networks’ critically acclaimed drama series MASTERS OF SEX. Nash, who will appear in a multi-episode arc, plays Louise Bell, a local AA - chairperson running Masters’ (Michael Sheen) court-ordered daily meetings. She fervently believes in AA’s message, and uses it to push Masters to reevaluate his life. Gilpin, who will also appear in a multi-episode arc, will play Nancy, a former medical student of Barton’s (Beau Bridges), who partners with Masters adding a second MD to the practice. Production on season four recently began in Los Angeles.