Danny Jacobs (Growing Up and Other Lies) has booked a recurring role and Stephen Root (King of the Hill) and Romy Rosemont (Glee) will guest star on the fourth season of Showtime’s drama series Masters Of Sex.

Starring Michael Sheen and Lizzy Caplan as real-life pioneers of human sexuality, William Masters and Virginia Johnson, Masters of Sex Season 4 will begin in 1968, and will take viewers into the “swinging ‘70s” during which time the characters will take on new partners both professionally, personally and sexually.

Jacobs will play Bob Drag. Bob has worked for Little Brown, Masters and Johnson’s publisher for years, but his relationship to Bill and Virginia’s work evolves beyond the editorial when he becomes patient zero in a new study at the clinic. Root and Rosemont, who are married in real-life, will guest star as Harvey and Marcia Toplin, co-owners of a sex clinic and the funhouse mirror image of Masters and Johnson. The Toplins have opened their own sex clinic where they are appropriating Bill and Virginia’s proprietary therapy techniques.

Jacobs, a member of the Groundlings Sunday Company, co-wrote, co-directed, and starred in the ensemble comedy Growing Up and Other Lies, with Adam Brody, Wyatt Cenac, Josh Lawson and Amber Tamblyn, as well as the indie dramedy Humboldt County, with Fairuza Balk, Frances Conroy, Jeremy Strong, and Chris Messina. He’s repped by Buchwald & Associates, Authentic Talent and Literary Management, and Kaplan/Perrone.

Root is repped by Gersh and Brillstein. Rosemont is with Domain and Trademark Talent.

Masters of Sex Season 4 premieres Sunday, September 11 at 10 PM on Showtime.