'Masters Of Sex' Season 4 Spoilers: Showtime Casts Niecy Nash, Betty Gilpin [DETAILS]

"Masters Of Sex" is adding exciting cast members in season 4. Soon after announcing that 'Being Erica' actress Erin Karpluk will recur throughout the season as Bill Masters (Michael Sheen) and Virginia Johnson's patient, two more stellar actresses have been added.

"Getting On" and "Scream Queens" actress Niecy Nash joins the drama series as an Alcoholics Anonymous (AA) chairperson named Louise Bell, TVLine reports. She is in charge of running Masters' court-ordered daily meetings. Nash's Bell is a firm believer of AA's message and doesn't hesitate to push it on a stubborn Masters to reevaluate his life.

Sheen's Masters certainly needs to reassess his life after being charged with prostitution and a lawsuit in the season 3 finale.

Furthermore, "Masters Of Sex" has also cast "Nurse Jackie" actress Betty Gilpin in a recurring role as a former medical student of Barton Scully's named Nancy. Nancy partners with Masters in his practice resulting in the addition of another MD on their door. Of course, Nancy's addition won't go down well with Virginia Johnson (Lizzy Caplan) who will once again be reminded that she isn't a qualified doctor.

Season 4 will be set in 1968 and enter the 1970s as the show progresses. Characters on the drama series will take on new partners either professionally, personally or sexually.

Bill emerged a defeated man in the season 3 finale after Virginia left him for perfumer Dan Logan (Josh Charles). Worse still, his wife Libby (Caitlin Fitzgerald) confessed to knowing about his years of infidelity.

To top it all off, Dennis' parents filed a lawsuit against him after learning that he showed their son pictures of men and women's genitals. Additionally, sex surrogate Nora informed the police that Masters was paying her for sex.

"Masters Of Sex" season 4, episode 1, premieres on Sunday, Sept. 11, at 10 p.m. EST on Showtime.