Spoilers: Do not read on unless you’ve seen the Season 3 finale of “Vikings,” titled “The Dead.”

In the season three finale of History Channel’s “Vikings,” we saw Ragnar Lothbrok (Travis Fimmel) fake his own death in order to infiltrate Paris and allow his warriors to ransack the purportedly impregnable city, only letting his son Bjorn (Alexander Ludwig) in on his plan. This manipulation prompted several of his loved ones, including his ex-wife Lagertha (Katheryn Winnick) and shipbuilder Floki (Gustaf Skarsgård) to make some shocking confessions beside his coffin, with Floki admitting that he was the one who murdered Ragnar’s closest friend, Athelstan (George Blagden) — leading to an ominous confrontation between the pair in the episode’s final minutes.

As a weakened Ragnar and his allies sailed back to Kattegat with their treasure, his brother Rollo stayed behind, ostensibly to keep things clear for the Vikings to return and raid Paris again. But unbeknownst to Ragnar, in an attempt to prevent any further attacks, Emperor Charles (Lothaire Bluteau) made a deal with Rollo (Clive Standen), offering him land and his daughter Gisla’s (Morgane Polanski) hand in marriage to turn against Ragnar and help the Franks defend the city, setting the stage for another fraternal showdown in season four.

Variety spoke to “Vikings” creator Michael Hirst about the surprising twists of season three and his plans for season four.

We witnessed a huge amount of mistrust from Ragnar’s allies following his baptism, and in the finale we saw that it was all part of a long con, but was there any part of him that was genuine in that desire? And how will that affect his relationships going forward?

They’ve understood that the death of Athelstan has affected Ragnar very deeply. They are concerned about the influence that Athelstan had on Ragnar and this confirms some of their worst fears. Part of it is true — I think that Ragnar has been baptized in order that he can meet Athelstan again when he dies. I think there’s a genuine connection there that’s real. On the other hand, what they don’t know and what he hasn’t told them is that he’s figured out a way of getting into Paris and also making The Seer’s words come true, that “not the living but the dead will conquer Paris,” and it’s later that Bjorn says that “he told us he would get into Paris and he’s done it.”

So, you could say that he’s taken a chance with his reputation, but on the other hand his reputation is also to achieve what he set out to do and this is exactly what he’s done. There are many ways of looking at that moment and I’m pleased to say that with the show now, hopefully any scene has multiple layers and can be looked at in different ways. And sometimes in the show you simply can’t tell where it’s leading. You see these events and it’s only later that they begin to fall into place and I think this is one of those strategic and rather wonderful moments.

The other thing is the emphasis that it puts on the profundity of religious belief at the time. Ragnar knows, from talking to Athelstan, that for the Christians it’s vital to bury a Christian soul in hallowed ground, and especially for someone who’s converted. This is the way that they’re going to try and neutralize the Viking threat, to them. He pretty much worked out that that’s what they’d have to do in taking into the city, so it does operate on different levels. And it’s nice that it’s sort of contradictory too. That it’s both cynical on the one hand and yet it’s about real things and passions.

This season, we’ve seen a Ragnar who’s physically weaker and more emotional than we’ve ever seen before — was it a major goal to explore his vulnerable side this year?

Yes, absolutely. Going right back to almost the first scene of the season when he’s talking to his son about kingship, we understand that he’s not looking forward to it. He’s a thoughtful guy and he understands something of the burden that this is going to cause him, and boy, is it a burden. He suffers and he’s marked by kingship and even though he succeeds, it’s at a very high personal cost. I did want to see that. I did want to see someone who’s also tormented, that doesn’t find things easy any more, who looks back nostalgically to his farming days, who still talks about that — because obviously then life was much simpler. You see how easy it is for power to slip away. You see how difficult it is to maintain that kind of momentum that he had when, by and large, he didn’t fail. He does of course — cleverly, if you think about it that way — set up Floki and other people to fail in the first attacks on Paris. That’s a cynical view, but it’s certainly the view that Travis takes. You can see in the way he plays it that he’s looking at this and he’s thinking, “I knew this was going to happen.”

So, yes, I absolutely wanted to show someone who got smashed around a bit and suffered. But I have to say, obviously we’re setting up another huge confrontation with his brother. And his brother is going to say to some important Frankish people, “It’s not just going to be a Viking army coming up the Seine towards us. It’s going to be Ragnar Lothbrok,” and even though we end season three with Ragnar hovering between life and death, one should never underestimate Ragnar Lothbrok.

As you said, we’ve seen Rollo take up arms against Ragnar before when he thinks he can win, so how will this rivalry differ?

I think that in season three, a significant part of Rollo’s arc was when he went to The Seer and said that his life was useless and that he would never succeed, that he would always live in his brother’s shadow, that there was no real reason for him to be alive. The Seer says “if you could see what I can see when you reach Paris, you would be dancing naked in the sand,” and for the rest of the season he’s trying to puzzle that out. It certainly doesn’t make any sense in the beginning, doesn’t make any sense when they’re losing and everything, so it’s only when he’s made this offer — [and] it would be very difficult for himself to turn down this offer anyway — the key fits in the lock and he realizes as he takes it that that’s what The Seer meant.

If he’s going to do this, he’s got to go the whole hog, so he’s gone into that with the Franks and that’s not going to just be a game of convenience. If he does this, this time — it’s a second betrayal, but it’s a much bigger betrayal. He’s been promised huge amounts of land. In fact, the land is what we now know as Normandy so it’s very big, and the title and a bride and everything… he’s going to want to make that work. He’s going to want to prove that this is what the gods meant and this is why he should be dancing naked on that sand. In fact, Clive wants to dance naked on the sand, but it is hard to get Clive to put any clothes on anyway… But the conflict now is at a much higher level, but it has different sorts of ramifications too.

Ragnar confronted Floki about killing Athelstan in the finale. Their relationship has been strained for a while, but what can you preview about their dynamic in season four?

It’s clearly an issue that is going to have to be resolved. It’s a huge thing in terms of who Ragnar himself has lost along the way: his closest confidants; Torstein [Jefferson Hall] probably the last of that first band of warriors; Athelstan, the only person he could confide in, really; and now Floki, his boat builder. This is clearly devastating for him, but even so, you might wonder how long he’s known and why perhaps he hasn’t done anything about it before. All these things are pertinent to what happens in season four, but certainly it’s a big, big issue and it will feature in a very, very important way in season four with hopefully some unexpected results.

What went into the decision to kill Athelstan? His death was obviously a major catalyst for both Ragnar and Floki in the back half of the year, but was it always the intention to kill him in season three? I recall you saying that you initially intended to kill him in the first season.

Yeah. I looked back at my original outline and he was dead by episode four, but then again, Ragnar was dead by episode ten… When I was writing the bible of season three, I realized that I had to deal with Athelstan’s central issue because I couldn’t have him flip-flopping many more times. I’d done that. He’s had his spiritual agony, so I would just be repeating myself if I continued that, so then I started thinking, “well, how do I resolve that? What’s the best way for him?” Then I thought it was cool that he’d thrown his lot in with the Vikings. He’d left, chosen to go back to Scandinavia with Ragnar rather than staying with Judith who was having his child; Ecbert, who loved him; his own country. And it’s at the point when he’s thrown in his lot with the Vikings and the pagans that Christ speaks to him — or he believes that Christ speaks to him — and of course these things are very personal and nobody else sees him being blinded by the light, just as nobody else sees the blood running out of the wooden statute from Floki’s view.

So it’s personal, but still, God certainly speaks to him and then I thought, “so what do I do now? I’ve got this loose cannon, certainly a loose priest, and it’s not plausible that he would be able to get that to England on his own. It’s not plausible that he would survive in a pagan land very long.” Of course, he kind of knows this because he says to Ragnar, “I don’t care what happens to me now.” So, martyrdom was, I thought, a really good way for him to die because he embraces it and it’s the most wonderful Christian thing to become a martyr for his faith and he goes to his martyrdom joyfully. There’s just something in those wonderful moments between Floki and him that somehow registered and it was very moving. George was in the studio [recently] and he was extremely grateful that he kept coming back as a ghost or a vision. But he was great and it’s a sad thing — the character grew, obviously, in importance but George grew as an actor and by the end I thought that was an incredibly powerful, poignant demise and I was pleased for him, because he’s a star now.

Ragnar withheld the truth about Paris from everyone except Bjorn — will that create further trust issues with Lagertha?

The issues between Lagertha and Ragnar could cover three beaches now… Of course [it will], and there’s a kind of humiliation in opening your heart to someone when they’re dead, and she just confessed that she still loved him. And now you think he’s lying there [in the coffin] with a little smile on his face. That’s a terrible thing. So, yeah, she has to navigate some difficult emotional — as well as political and physical — issues and it’s another one. Her relationship with Ragnar will continue to be changeable, but in a way, whether they like it or not, they’re part of each other.

Will Lagertha try to regain her Earldom in season four?

You’ll have to wait and see. [Laughs.] What I can say is that yes, the end game, the result of all those issues will be something quite unexpected.

How you intend to top the scope of season three? You’ve been getting bigger every season, so what could be more ambitious than the Paris raids?

We have these two great guys who choreograph the fights and the battles, and they’re — like everyone else who works on the show — very, very creative… But I go to them and I say “what can we do that might be even bigger, more spectacular, more interesting, or more unexpected than we’ve done?” And we sit down and we try and devise something the Vikings might do that we haven’t seen them do before, some challenge that they have that seems insurmountable. That’s one of the things that we’re always looking to do. I thought episode eight this time, in that sense, was just unbelievable and awesome. Of course, we used more CGI than normal, but I think we’ve kept faith with the founding principles of keeping it as real and character-driven as possible. In that sense, the big, big confrontation between Ragnar and Rollo, which is likely to be definitive, is at another level again. Last time it was just one fight, one battle between them, but this time there’s much more at stake and it’s got to be a lot more than that. So, the personal issues, the stakes are higher… I love these people anyway, and taking them on new adventures and delving deeper into their psychologies and their love lives is fantastic.

We’ve seen King Ecbert (Linus Roache) sink to new depths of Machiavellian scheming this season, so what’s ahead for him next year?

Well, more Machiavellian stuff, needless to say, but based on a perfectly reasonable, historically correct idea that he wanted to be king of kings — he thought that would make a big difference for England, which it ultimately did. It meant that Alfred the Great, when he came to the throne, inherited a large kingdom that enabled him in the end to deal with the Vikings in the way the smaller kingdoms couldn’t. So even though Ecbert is cynical to say the least, and Machiavellian, he has numerous positive points. He’s obviously very clever, very educated, very intelligent, but I think that it would be fair to say that these Machiavellian designs and things he does do start to impact his soul. What we might discover is that Ecbert is not just clever but has a soul, and he gets up to some pretty devious and interesting things.

What are you most proud of, looking back at season three?

I think we promised to deliver something bigger and better. I promised that not only would it be more spectacular, but we’d be more involved in the lives of our major characters. I believe that we’ve delivered that, so I’m proud of the whole season and everyone else that’s contributed to that. And I’m pretty proud that I smuggled some lines by T. S. Eliot into the show and no one’s noticed.