The swinging ‘60s are back! Showtime’s sexually charged drama series “Masters Of Sex” returns with a brand new Season 4 on Sunday, Sept. 11 at 10 p.m. EDT.

Sex research pioneers Dr. William “Bill” Masters (Michael Sheen) and Virginian Johnson (Lizzy Caplan) return to TV after the pair had a falling out last season. Bill was slapped with a lawsuit and prostitution charge, while Virginia left her long-time partner to start her life anew with perfumer Dan Logan (Josh Charles).

What can we expect in Season 4? Check out 8 things to know ahead of the “Masters Of Sex” premiere below:

1. Episode 1 Synopsis

The Season 4 premiere will pick up some time after the events of Season 3. The official synopsis of episode 1 reveals that Masters and Johnson will search for their purpose in a world without one another. They will turn to their work when their personal lives come crashing down. Although Dan made a sweet proposal to Virginia, she isn’t happy being with him.

Meanwhile, Libby will find herself alone for the first time since her marriage to Bill. She will discover that she has some unexpected allies.

2. Episode Titles

Showtime released the titles of the first couple of episodes of “Masters Of Sex” Season 4:

Episode 1 – “Freefall”

Episode 2 – “Inventory”

Episode 3 – “The Pleasure Protocol”

3. Bill And Virginia Reunite!

Although it seemed like their broken bond was irreparable, “Masters Of Sex” Season 4 will see Bill and Virginia reunite and repair their damaged relationship. It won’t be long before they work together. However, restoring their personal connection will take much more time.

via GIPHY

4. New Characters

The Showtime series has cast a number of interesting characters to spice up Season 4. Niecy Nash will play an Alcoholics Anonymous (AA) chairperson who is in charge of Bill’s court-ordered daily meetings.

Other characters to be seen will be the AA chairperson’s husband played by Corey Reynolds, Bill’s long-lost love played by Broadway vet Kelli O’Hara, a singer named Sammy essayed by Andre Royo, a high-powered lawyer portrayed by David Walton, a new-age guru named Jade played by Camryn Manheim, a new patient named Darleen Connolly played by Erin Karpluk and Betty Gilpin as a new doctor who joins Bill’s practice. Whew!

5. Bill Is At Rock Bottom

Bill will do interesting things when he hits rock bottom. After losing his family, his lover and almost losing his practice, the surgeon and boxing aficionado will undergo some changes. His perspective will alter and he will smoke weed.

6. Libby Undergoes A Transformation

Free from the shackles of her marriage with the doctor, Libby (Caitlin Fitzgerald) will undergo a transformation. She will have multiple sexual partners.

7. Bill In Court

While Dr. Masters didn’t lose his practice entirely in “Masters Of Sex” Season 4, he is going to have a long legal battle ahead if he wants to remove the lawsuit and prostitution charge from his record.

8. Important Historical Events Will Be Shown

“Masters Of Sex” has always depicted major historical events. In the upcoming season, the series will show the feminist protest of 1968 at the Miss America pageant which involved bra-burning.

You can watch the premiere for free on Showtime here.

“Masters Of Sex” Season 4 premieres on Showtime on Sunday, Sept. 11 at 10 p.m. EDT.

Masters of Sex “Masters Of Sex” Season 4 will see Bill and Virginia mend their broken relationship. Catch the season premiere on Sept. 11 on Showtime at 10 p.m. EDT. Photo: Showtime