As I explain more in-depth in my review of the Nurse Jackie season four premiere - which will go live on TV Fanatic the instant this Sunday's new episode concludes - this is a show in need of significant change.

I say that as a fan, but also as a viewer who has grown a bit frustrated by the lack of consequences Jackie Peyton has suffered over three seasons, despite some seriously unethical behavior.

Fortunately, someone at Showtime clearly agrees. Because, wow, almost every character undergoes a major shift on the installment titled "Kettle Kettle Black Black."

The most significant development is given away in this Nurse Jackie season 4 promo: the title character is off to rehab. But what prompts such a decision? It has to do with guest star Billie Joe Armstrong.

Among other changes you can expect:

• Someone is pregnant.
• Someone is in need of a serious shave.
• Bobby Cannavale makes his presence felt as Dr. Mike Cruz, who represents the company that has purchased All Saints...
• ... and he has some surprising news for Gloria.
• Eddie makes a drunken confession.

Looking ahead to episode two, meanwhile, a star athlete makes one of the more random guest-starring appearances in recent memory. Hint: he plays basketball for a living, but he plays baseball on the show.

Let the guessing game begin, and tune in this Sunday for the Nurse Jackie season premiere.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.