As any series ventures into its fourth season, changes inevitably are made in either cast or storyline to keep the show feeling fresh and Showtime's dramedy "Nurse Jackie" is no different. Always fearless in taking the show places we didn't expect, Executive Producers Linda Wallem and Liz Brixius kick off season four this Sunday by having Nurse Jackie Peyton (Emmy winner Edie Falco) go where the series has never gone before - rehab.

Jackie trying her best to sober up at a time when her life is falling apart is not the only thing new about the coming episodes as our Jim Halterman found out when he chatted with Wallem last week. Besides a new cast member, Bobby Cannavale, who is brought in to shake things up at All Saints' Hospital, mainstays like Akalitus (Anna Deavere Smith), O'Hara (Eve Best), Zoey (Merritt Wever) and Cooper (Peter Facinelli) are also going through various comedic and dramatic changes in their respective lives which leaves "Nurse Jackie" feeling anything but down and out.

Jim Halterman: A general question to start, since the show is partly a workplace comedy, is that something that you and Liz were fans of when you created it or was it more organic than that?

LW: I think it's more organic. I'd love to be high-falluting but you know what? It just sort of happened and so much of it is the chemistry of our actors that we have. This show really taught me; boy, if you cast it right it's like a Super Bowl team. Everything just sort of naturally happened and somebody like the genius of Merritt Wever when she's sitting at her desk in the nurses' station, she creates a whole world by herself. Zoey's world about what pen she's using and how she sits and how she reacts to everybody. It's really within that little nurses' station and it's been wonderful to watch [the actors] just doing what naturally comes and all of that, which is just so funny when people spend more time with people you work with than you do with your own family. But, no, they just kind of did it and then we could write towards that sometimes.

JH: Did you and Liz ever think that if you didn't take this step to rehab with Jackie that she would become unlikable because she wasn't even trying at this point?

LW: No, I just think it all came together, that it felt right. Showtime was way behind it. It just felt like this is a good turn to take in the periods right now, fourth year, because, again, hats off to Edie and that potency that she plays as an addict and a complicated character. This was just the fun of throwing her another complication because it's really fun to watch her...I think it's in episode three where she comes to work and she's distraught because she can't believe, for the first time, Coop hurt her feelings. I mean, we love that because what's the worst thing that could happen to Jackie today? It used to be, oh, I don't know, 'I killed a guy.' Now it's 'Oh, my God. He hurt my feelings.'

You know that slippery world of having feelings now that you're sober. I think that's going to interject a lot more comedy this year. You know, we took a hit the last couple of years for not being comedy enough. It's like, well, so what, I don't care what people say. But it's just naturally what happens when you start to recover things are going to lighten up a little bit. So, it's really fun comically in a dark comedy to see someone like Edie have to deal with that stuff. She did a genius job.

JH: Had you always had the plan that maybe around this time in the series this is when you would take her to rehab?

LW: It was the opposite. I was so adamant about 'She's never going to rehab! No way! Never!' And after last season, I don't know. It just hit me and it was like our own experiences of sobriety...during the break in between [seasons] three and four we had this long talk. We started to talk about what that would look like. I had to divorce myself from my own experience of rehab. The trick is how do you make rehab feel fresh and different and see a powerhouse like Jackie in rehab. So, we just stripped it down, made it very simple.

You could see that someone like Jackie who was as determined to be an advocate for a patient, she's going to be as determined to kind up and figure this out finally and maybe give herself a break from what it feels like to be underneath that heavy load of addiction. Then to see Edie Falco, to see Jackie. She's smiling more. It's remarkable. I stood there with the monitor on keeping going, 'Oh, man. Poor Edie.'

JH: I'm curious which came first, Bobby Cannavale or the character, Dr. Michael Cruz?

LW: Oh, Michael Cruz. The idea of bringing in the character; that just was a lightning bolt. That just really told the truth of what's going on in health care in New York and we just thought it was funny that a company that has holdings in firearms, baby food, and hospitals...that's the new wave, right? So, what happens when you have to throw in this hotshot who is a doctor but also a money guy? Edie actually brought up Bobby's name. We were like, are you kidding? We would be over the moon to have him.

He just finished 'Mother Fucker With a Hat' [on Broadway] and he came in and we talked to him. We were just 'Please do this.' We kind of laid out, 'Look, there is a personal story, too, that's going to be a big part of the arc of this season with him...' He just was on board from day one. I think he was so excited about acting with Edie again. He was a really fun, different energy to throw in to all things. It was just such a great. I'm beyond grateful for Bobby. It was just a blast; exactly what we wanted. Showtime was really happy with him, too.

JH: From the episodes I've seen, there is no sexual relationship between Cruz and Jackie when you would think Jackie would somehow try and make it about sex especially where she's at in her recovery.

LW: Exactly. We've been down that road with her, too, already with Eddie (Paul Schulze). When Lizzie and I were laying this all out, part of the bummer of getting sober is all your tricks don't work any more. So, Jackie is like 'Oh, shit!' The lying doesn't work any more so it's like you've got to start...'ah, I've got to start telling the truth? Oh, this is gross.' That's fun to see Jackie going, 'Oh, oh, I got to do this? Geez.' Some stuff just chokes in her throat sometimes but she's got to ask for help. She's going to lose her kids. She needs a letter of recommendation from her new boss that doesn't even know her.

JH: You mentioned Merritt Wever and I wanted to ask if you have written towards her talents from the start. Even in the pilot you can see what she brings to the show without saying a word.

LW: Oh, yeah. You've got to tee her up right. It's important for Zoey that she's in situation where...it's funny. We did this once when people were asking what do you do when people roll their eyes at Zoey. Merritt said, 'Well, I don't think Zoey ever sees people rolling their eyes at her.' That's exactly right. You've got to put her in situations where Zoey can be high on her horse. She might look ridiculous but she cares so much. But she can be terribly wrong and her timing can be awful, which is hilarious. Merritt is a genius at the end of a scene just doing a little flare on it that none of us would ever think of. It's just some weird piece of business. You go, 'Oh, my God, I love this woman.' She's amazing.

JH: Jackie's kids actually scare the hell out of me because I just think they are both just going to end up such a mess. They are already a mess in their own ways and it just breaks your heart because you could easily blame Jackie for everything. She hasn't been the best mother.

LW: When you see your kids go over the edge you realize, 'I'd better wake up.' It's a big reason why Jackie has to really do the right thing this year especially with Grace. She's on the same path. All the little things that have happened with the anxiety and all of it, that [Jackie] realizes 'I've got to really be there for her.' So, it takes a really special little actress. The little girl, Ruby [Jerins], who plays Grace, is the happiest child you'll ever meet but she just goes there so fast. You go, 'Oh, my god.' She's just a remarkable little actress who can pull this off.

I can't wait for you to see the last couple episodes. There is a journey that her and Jackie take and at one point and I'm not going to tell you where, they actually smile at each other and it's remarkable. We've never really kind of seen that and to see kind of a truth at one point, it's really remarkable. It's a huge moment, I think for Jackie and for Grace, when you see a parent-child, wow. She nipped that in the bud, just in time. I'm hoping that that's how it looks. Needless to say, [Ruby] smiles in her sleep. She's not that girl.

JH: I have to ask about your brother (Stephen Wallem) because Thor is so fun. He's such a big teddy bear but I feel like we don't always get to see a big side of Thor's life. Do we get to see a little bit more this year?

LW: We get to see some, not as much as what I would love. I could do a spin-off called Thor. I swear, in my mind, what his life looks like and what I would love to do with that...there's not enough time. There's so much I do want to show, would love to show more of his life and how he handles his diabetes and all of that. I was so glad that we were able to share that truth. Yeah, I think he's remarkable.

"Nurse Jackie" airs every Sunday at 9:00/8:00c on Showtime.