If you haven't seen Sunday night's installment of Breaking Bad—the premiere episode of the second half of the final season—stop reading now. Something big and surprising happens at the end of the episode, and that's what this story is all about. I don't want to spoil it for you. Come back after you've caught up.

Now that we've weeded out the stragglers, let's talk.

Sunday's Breaking Bad premiere picked up right where last season left off: with detective Hank Schrader realizing on the toilet that his mild-mannered brother-in-law Walter White is actually Heisenberg, a murderous, meth-cooking criminal mastermind of epic proportions. It was like Ahab finally spotting his white whale.

What most viewers probably didn't expect was that Hank would decide to confront his mark—or that Walt would discover he was being hunted—anytime soon. I assumed that Hank would take his time—that his cat-and-mouse game with Walt would be a major part of the final season's overarching narrative. Ever the professional, Hank would observe, investigate, and wait for the perfect moment to spring his trap.

How wrong I was. After spending a few days in a state of strained, red-eyed shock—he calls in sick after plowing his car into a neighbor's yard—Hank decides to plant a GPS tracker on Walt's car.

Meanwhile, Walt is happily retired—until his cancer comes back. As he leans on the toilet between bouts of vomiting, he notices that his copy of Leaves of Grass is gone. Then Skyler tells him that Hank is working a case from home. Suspicions aroused, Walt walks outside and reaches under his bumper. Bingo. The tracker.

This sets up the remarkable encounter at the end of the episode. Walt stops by Hank's house. He's officially there to check up on Hank's “illness,” but his real purpose is to detect if Hank is on to him. He seems to be. Walt is dismayed. He turns to leave. Then he reconsiders. He stops. He pulls the GPS tracker from his pocket. And he asks Hank point-blank if he's under investigation.

Seconds later, the garage door is closed and Hank is slamming Walt up against it, accusing him of being Heisenberg.

Words can't really do the scene justice. It is one of the richest, saddest, and most expertly executed in the history of Breaking Bad. As Hank, Dean Norris hovers somewhere between a sob and a dropkick, blending shock, betrayal, rage, and despair in equal, utterly believable measure. And Bryan Cranston is immaculate as usual. When he shifted in the episode's final line from "a dying man who runs a car wash" to a crime lord threatening Hank—"If that's true, if you don't know who I am," he hissed, "then maybe your best course would be to tread lightly"—I got the chills.

Wanting to know more about how the scene developed—and how the coming episodes will build on Sunday's turbocharged start—I gave series creator Vince Gilligan a call. He was gracious enough to take me behind the scenes and explain exactly what he and his team were thinking.

Below are edited excerpts of our conversation.

The Daily Beast: Were the two halves of Season 5 written separately, or was it all one arc? Did you have to come back to the writer’s room after writing the episodes we saw last year and figure out how to start the final half-season?

Vince Gilligan: We did indeed break them in half. We did not write them straight through. We took a little break of a month or two, and we thought at the end of our first eight that we would have an easy road ahead of us—that it would kind of write itself. But then we got back for the final eight and were like, oh shit. It was really hard.

The final scene of the last season was Hank finding Leaves of Grass and realizing that Walt was W.W. What were your options at that point?

What’s funny about it is that we thought our options were limited. In a good way—in a way that was going to make life easier for my six writers and myself. We thought that the story path to the finale would be very clear to us. Very well limned. But unfortunately when we got back we realized this could go literally a thousand different ways. What were we thinking?

It seems like we have a few major confrontations awaiting us in this final season: Walt and Hank, Walt and Jesse, and perhaps Walt and his cancer. Let’s talk about Walt and Hank first. Walk me through the process of deciding to have them confront each other so early in the season.

We knew when we got to the end of the first half of the season that Hank is onto Walt now. He’s sitting on the toilet. He’s reading Leaves of Grass. But then it’s like, what is Hank’s next move? Does he keep it secret? Does he go outside and just shoot Walt in the head? There are a hundred decisions right from the get-go. Then the question is, if Hank starts researching and investigating Walt, when does Walt find out that Hank’s on to him?

Everyone who sees that first episode says to me, “My God. I didn’t think these guys would come to a confrontation so quickly.” And the funny thing is, we didn’t either. The writers and I, just like the viewers, we all said, “When Hank and Walt are nose to nose and toe to toe here, and Hank is accusing Walt of being Heisenberg, when does that come? Is that the very final episode? Well, it can’t be the final episode. Is it midway through the final eight? When is it?” That’s a surprisingly hard part of the job—figuring out how to portion out plot. We’ve spent thousands of man-hours struggling with those very questions.

I thought you were going to withhold that confrontation for much longer. That would have been the standard thing to do—to have Hank trailing Walt without Walt's knowledge and slowly piecing it all together.

In our initial breakdown, we had it broken up into eight equally sized squares; you know, what’s going to happen where in these final eight episodes. And in our first version we thought that Walt wouldn’t know that Hank was onto him until about the halfway point.

But as we talked about it, the more we realized: nope, it needs to be in the first one. Because we've got a shitload of story left to tell. And we’ve only got seven more episodes after this one in which to tell it. So we’d better make hay while the sun is shining.

That's why these final eight episodes move faster than any stretch of eight episodes that we’ve ever had in the history of the show. Once this thing gets going, and it gets going very quickly, as you’ve seen, it just rolls along like gangbusters. It has to because we’ve got so little time left.

It seems like Walt and Hank are heading for some sort of uneasy truce, which is much more interesting as a viewer than just waiting around for the inevitable confrontation.

Yeah. Well, it may seem that way, and maybe that’s where we’re heading—or maybe it isn’t [laughs].

How about the scene itself? I thought Dean Norris and Bryan Cranston were absolutely at the top of their game. Was it hard to strike the right tone—that mixture of shock and sadness and rage and menace?

I tell you, that’s all credit to the actors. Some scenes are harder to write than to act, and some scenes are the opposite. This is a good example of the latter. It’s one thing to write that "Hank reacts with a mixture of outrage and anger and sadness and betrayal"... you can put all those descriptors into a paragraph of writing, but it’s much harder for an actor to find that mix and communicate it to the audience in as few words of dialogue as possible.

And damned if Dean Norris didn’t accomplish that. He played that scene so beautifully. I think it’s one of the finest scenes he’s ever played for us. He and Bryan, who directed the episode, took what on the page is easy to communicate intellectually and they translated it into something the audience can feel viscerally. It’s a real magic trick, and I’m not quite sure they how managed to pull it off. But they did indeed.

You've said that Breaking Bad is a show about one man's transformation from Mr. Chips to Scarface. Is Walt entirely Scarface now? How much Mr. Chips is left?

That’s an interesting question. I think Walt was his closest to being entirely Scarface—or entirely Heisenberg, to be more accurate—at some of those low moments of high drama in the first half of Season 5, and maybe at the end of Season 4. I think he’s a man in retirement now, when we meet with him in this first episode. He wants to be a car wash owner. He wants to beat his cancer. And I think when he realizes Hank is onto him, and he says that great dialogue that Peter Gould wrote—“My right hand to God. I’m just a guy who owns a car wash who’s dying of cancer. That’s all I am. What’s the point of coming after me?”—I think as smart as Walter White is, he is truly bewildered by why a family member, a man that he loves, who ostensibly loves him, or used to love him, would come after him so vehemently. It doesn’t quite compute for him, at least in my estimation.

He ends that moment as Heisenberg, when he says, “My advice would be to tread lightly.” But I think up until that moment, he doesn’t really want to be Heisenberg any more. He’s done it. He’s accomplished it. He’s built his empire. Now he just wants to hold on to his empire, or what’s left of it—the spoils of it. And he wants more than anything now for his family to love him, to be in a state of affection for him, when he finally succumbs to cancer, whenever that may occur. And this is a really terrible development, because it puts all of that in danger.

I have a suspicion that Walt might not get his wish there. Why did you decide to have his cancer come back, and how much of a role is it going to play this season? It’s been on the backburner for a while now.

It has been on the backburner. But my writers and I don’t like leaving loose ends. Cancer was the plot engine that got this whole story going in the first place, and it felt wrong to us to not address it again. It felt proper and fitting to us that it might rear its ugly head yet again.

And as you can imagine, with a plot development like that, it only complicates matters. It makes the morality of the story more complex in the sense that Walt has a point. It’s very much a villain’s point of view, but it’s a point nonetheless when he says, “Look, I’m dying of cancer. I’m never going to see the inside of a jail cell. Why do this thing, Hank? Why ruin our family?” It’s kind of a douche bag point, but it has validity nonetheless. We love those kinds of story complications, and that’s as good a reason as any to bring his cancer back.

How about Jesse? In Sunday's episode we saw him weeping, wracked with guilt, and trying to give away the millions he earned in the meth business. He has always been the moral center of the show. Will he continue in that role to the end? I've always thought the final confrontation would be between him and Walt.

Jesse is not fit for the meth business, and I think we all know that. If we didn’t know that before, we know it now. He’s got too finely tuned a sense of morality to be a criminal. It was a mistake for him to be a criminal from the get-go.

And to be fair to Walt, Walt didn’t start Jesse down the path of cooking crystal meth. Jesse was already doing that regardless. But Walt made his life so much worse. And that’s one of Walt’s unforgivable sins, and one of the deep sadnesses of the show: that Jesse didn’t have a better mentor than Mr. White. He didn’t have this man tell him “you deserve better than this.”

And now we’re at a point where Jesse just can’t live with the consequences of his actions. He’s got this terrible guilt that will not be ameliorated. He tries to give away this blood money, as he calls it, and indeed, that’s the name of the episode. But nothing seems to help. It just won’t be expunged. It won’t go away.