"Breaking Bad" just ended its fourth season in memorable fashion. You can read my review of the season finale here, and I spoke with the show's creator, Vince Gilligan, about everything that went down and some of his plans for the series' final 16 episodes, all coming up just as soon as I spend time in an electrician chat room...

We have to start at the ending, with that shot of the Lily of the Valley plants in Walt's backyard. This is a very, very bad thing he's done, isn't it?


Yes it is. Walt has come a long way in 46 episodes, that is for sure. But he had a reason for doing it. As bad as it is, my personal take on it is that it was not about murdering a child. It was about making a child very sick but making it seem, more importantly, to Jesse that a child who was very close to him had been poisoned with Ricin. To our way of thinking, it was a very cold-blooded and yet pragmatic way of getting Jesse back in Walt's sphere of influence. It was a very big gamble that Walt was taking, to essentially make Jesse think he had poisoned this child, so Jesse would come to him, ostensibly to kill him, but then to ultimately hear him out and get back on Walt's side. It was a very big gamble that could have ended in Walt getting his head blown off by Jesse, but also a very, very dark secret that goes pretty much hat in hand with the secret that Walt keeps from Jesse about Jane - his guilt about Jane's death. Walt's a pretty bad guy these days, but as usual, everything he does, he does for a very specific reason, cold-blooded though it may be.

I want to get into the mechanics of the plan that Walt hatched. A big deal is made in the previous episode about the chain of custody of the ricin cigarette. What happened to it?

I think Jesse had the right idea. I think it was lifted off him by Huell. When he comes to Walt in the previous episode, and Walt asks how on earth would he could have done it, and Jesse says, "The big man mountain security guard of Saul's just had to see me, and he pats me down. You got him to get it off of me." So having done that, he could've just flushed it in the toilet, because as we find out, the child wasn't poisoned with ricin, he was poisoned with something else.

And Walt was somehow able to get access to Brock, to give him the berries.

Yeah. That part's probably the trickiest part. I can't remember the specifics, but we worked it out in the writer's room. He technically had enough hours to do it. How he found his way over there unseen is probably a little improbable, perhaps, but not impossible, is the way we figured it.

Well, one of the things I found interesting was that even earlier in the episode, before we find out about the Lily of the Valley plant, there's the scene where Walt goes to the house, and he sends his neighbor in, basically as the canary in the coal mine. So there's a couple of points in the episode where Walt is risking innocent civilian lives to protect himself.

That's true. And by the way, the little old lady next door is my mom. (laughs)

Was that bit there to set up the idea that Walt has already moved past that point, so it'll perhaps be a little bit less out of character when you then see the Lily of the Valley shot at the end?

Yeah, I think so. Walt has been a dark guy for a while, but he's definitely darker than he's ever been.

What exactly causes Gus's incident of Spidey-sense in the parking garage that keeps him from going to the car?

I think with that, he finds out in the previous scene in the chapel, he knows his lynchpin remaining meth cook is acting up, and hears this child's in the hospital, figures he has to go talk to the kid, get him right with Jesus, get him cooking, despite what's going on in his personal life. I think his Spidey-sense is all about the way Jesse looks at him in the chapel when he says the little boy's not sick, he was poisoned. That in and of itself sounds strange and sounds too coincidental not to be somehow involved with Walter White. I think his Spidey-sense keys off of Jesse's strange behavior in this hospital chapel.

Well, watching that episode, you have set all of us up to believe what Jesse believes, which is that Gus has poisoned him. It definitely makes more sense from the perspective we have now, but at the time, we don't quite know that.

I think it works on both levels. At the time, if you believe that Gus did indeed poison the little boy, then what you'd assume if you were Gus, when you get this kid alone and he says the little boy has been poisoned - then Gus is too smart to say, "Who do you think poisoned him?" But he's assuming Jesse will say, "I think Mr. White did it." But because Jesse never says who did it, or who he thinks, that's another reason for Gus's Spidey-sense, as it were, to tingle.

How hard was it to say goodbye to Giancarlo Esposito, and to Mark Margolis as Tio? The story had reached a point where they had to go, but was that hard for you as a writer and producer of the show?

Very hard. We knew months and months ago how we were going to end the season, so I called up both of those gentlemen and told them 5 or 6 episodes in advance and of course swore them to secrecy. It was tough. Having that conversation with Giancarlo was tough, I felt I was letting him down somehow, but he was an absolute gentleman and a mensch. He said, "It sounds like a fun episode. Whatever you've got to do for the story, man. I'll miss being here, but do what you gotta do to tell your story." But it's tough. It's like ripping off your own hand or something, because these guys are an integral part of the show. But as you yourself just said, it was time. In the sense of the old "Highlander" movie, there can be only one. I think we got to the point where the town wasn't big enough for the both of them.

And if the goal is to ultimately have Walt become Scarface, you can't have Scarface's boss around anymore. 

Exactly. At a certain point, you have to kill off Robert Loggia so Al Pacino can rise to prominence.

But on the other hand, you conveniently left Mike recuperating in Mexico. Have we seen the last of Mr. Banks?

I don't think we've seen the last of Mr. Banks. By the way, in keeping with the fact that people may die but don't completely leave us on "Breaking Bad," I would say that while we don't necessarily have plans for it at the moment, I can't imagine us getting through another 16 episodes of "Breaking Bad" without seeing Gus or Tio again in some flashback or another. I would hope, because it was just so much fun having those guys on the show. We historically do that: we bounce back and forth through time. I don't know why we couldn't do that again. But as far as Mike, you're right. Mike's still alive and kicking again down in Mexico, and I imagine we'll see him again next season.

Next season is 16 episodes, it sounds like they'll air over two years. How are you planning it out? Are you going to insert a specific break point around episode 8, 9 or 10?

I think so. It sounds to me like the thinking on the part of AMC is to split it into two seasons. So we'll try to have a proper cliffhanger, I would think, at the end of the first 8. Which I don't think would be too tough for us, because we try to do a cliffhanger more or less with everything we do. We try to play each one like it's our last as much as we possibly can. Hopefully, that won't be too tough.

That's another thing that occurred to me. By the time the negotiations came down to the wire, it was clear you were either going to continue on AMC or go to another network, but there was a chance when you were writing this episode that it might be the last episode of the show ever. Would you have been comfortable with Walt on the parking deck and then the shot of the White backyard being the end of the series, if it had come to that? 

I think I personally would have been, yes. I think an argument could be made that the end of episode 13 of season 4 is, in essence, everything - but one thing, perhaps - that we promised the viewer, or implied to the viewer from day one, which is the idea of taking Mr. Chips and turning him into Scarface. Walt is pretty much as bad as one could imagine at the end of episode 413. There are two big questions left wanting for answers: one is what is the state of Walt's cancer, and the other is what about Hank? Will Hank ever figure out who Walter White truly is? Those would be the only really, for my money, big questions left outstanding. If for some reason a meteor hit the earth or something and then episode 413 was the last episode we were ever gonna do,  I would feel pretty good except for those two being the only outstanding questions. However you slice it, I feel fortunate that we've got 16 more. I'm happy about that.

There's also the question about how Jesse will be if or when he finds out about Brock, about Jane, and about all the things Walt has done to him and the people he cares about.

Well, you're right. (laughs) Now that you say that, I can think of a few other outstanding questions. But having said that, something feels satisfying on some level to me about the way 413 ends, so if we had to end it there, I don't think it would be a terrible tragedy. But having said that, I've got a lot more I want to do with the show, so I'm proud to have 16 more episodes to play with.

Getting back to Walt's cancer, you're not going to tell me if it's back or not, and I don't want to know. But Bryan was coughing an awful lot in the last few episodes, which brings to mind the fact that much earlier in the season, Mike was coughing a lot for a while. I've been trained watching years of TV that there's no such thing as a coincidental cough. Was this a coincidental cough?

(Laughs)

Did Jonathan Banks just have a cold at the start of production?

(Laughs) You know what? I don't know quite how to answer that. I hate to sound coy, but sometimes there are coincidences and other times there aren't. I have to let that one pass unremarked, so as not to give too much away.

Well, that brings to mind something that became a running gag on the blog this year. Every little element of the show started being compared to the Chekhov's gun theory: Chekhov's throw rug, Chekhov's Ricin cigarette, Chekhov's .38 snub. You plant these things and then you pay them off later on. How far in advance do you have to work to introduce those things?   

The one with the rug, not so very hard, because it was all contained within one episode. But the Ricin cigarette, for instance - the short answer is, we try whenever we possibly can, we prefer the long set-up versus the short one. It pleases us. It satisfies us as writers when we can play a very deep game, and play it as many moves ahead as possible. To that end, setting up Tio as Gus's nemesis, that we didn't realize how deep their enmity towards each other was, we started that in earnest this season with episode 8. That was a pretty good lead time, five episodes ahead. But some part of me wishes it had been deeper still, maybe another season before that. Although you kind of get hints the very first time Tio meets Gus along with the Cousins, that the old bastard does not care for Gus.

And also in the flashback in "One Minute," he clearly has a low opinion of "the Chicken Man."

That's true. So we're proud of playing that long game. Sometimes, the game looks like it's been played longer than it truly has. As you just said, that flashback in "One Minute," I don't think we were thinking back then about how Gus and Tio would meet their demise. But we looked back over everything we'd done and we knew there was no love lost between those guys from day one when they first met. We realized we could build on that reality, and add to it and amplify it. The audience realized that these guys don't just dislike each other, they loathe each other. The deep game we try to play, sometimes it feels a little deeper than it truly is. Sometimes, we look around, see where we are and realize fortuitous bits of happenstance that we can build on.

Who was it, and how long ago was it, that came up with the idea that Tio's bell would detonate the bomb that would kill Gus?

In the writers room, it really is a group mind, and you often forget who came up with what. Though I will say in this instance I think it was me. I will take a little executive privilege here. I loved the idea of Tio dinging that bell and blowing up Gus. I think we talked about that at the very beginning of the season, and then we shelved it for a while, and then we came back to it.

This is the first time where I can think a Walter White plan actually worked. Pretty much every other time he's plotted to kill somebody, something's gone wrong, he's had to improvise and kill them at the last minute. This all went to form, at the same time that Walt has, as you say, gone to a very, very dark place. Thematically, is that a coincidence? Or is it deliberate in your mind that Walt could only succeed at that level when he becomes this evil? 

That's a very interesting question. I hadn't really thought of it in those terms. This world that he finds himself in, he doesn't find himself in this world by accident. He has made a conscious decision, starting in the very first episode of season one, to be a criminal, to be a bad guy and to live on the wrong side of the law. A guy as smart as Walt should realize pretty quickly that you don't play with fire and not get burned. What's the best way to put this? I'm hoping that when people watch this, they'll think this is the lost episode of the Roadrunner and the Coyote where the Coyote actually gets the Roadrunner. I guess it's a good argument you make: the darker Walt goes, the more chance he has of competing on a level playing field with Gustavo Fring. I hadn't thought of it in those terms, but I guess there is truth to that. This is yet another section of the very dark path he has long ago chosen to tread. So it's nothing new in one sense. In one sense, he's gone very dark indeed, but in another sense, this is the same path he's been on for quite a long time. It starts to feel somewhat inevitable, to me at least, that he would go this dark.

(Our phone interview ended here, but I had one e-mailed follow-up later.)

You've kept certain story points about what Walt is up to from viewers before (like Jesse still being in Albuquerque after Walt killed the drug dealers in "Half-Measures"), but never something this big, for this long. This is, if not a complete departure from your narrative style, definitely outside the norm, which is that we see Walt during everything interesting he's doing and know what he's up to. Why did you choose to tell this part of the story this way, as opposed to, say, letting us know from the start that Walt poisoned Brock and was manipulating Jesse?

I think it's because there's no bigger reveal than the fact that Walt would poison a child (albeit to save his own life and the lives of his family). That's the moment that truly makes him no better than Gus. Simply put, it seemed wise to me to save Walt's deepest, darkest secret until the very end.

Having said that, the lily of the valley is hinted at in episode 412 the week before.  Walt sits by his pool, waiting to die.  He spins his pistol twice in a row, and both times the muzzle winds up pointed straight at him.  Is this fate telling him to shoot himself?  But then, on the third spin, the muzzle points at the nearby lily of the valley.  This, to me, is the moment that Walt begins to get his bold (and reprehensible) idea of poisoning Brock.  Divine -- or devilish -- inspiration?  Who knows?

Alan Sepinwall may be reached at sepinwall@hitfix.com