They build, they build, they build. Kattegat has grown and it has grown large, from an earl’s village to a King’s capital to a merchant metropolis. It is a modern city, and it is a prize, and Queen Kattegat will defend it. She has set her people to building, building, building. They will build defenses. There are enough enemies within already.

Ragnar Lothbrok is dead, but he lives on. (I talk about that with Vikings writer Michael Hirst in this week’s postmortem interview, where he also answers your question about Bjorn and Astrid and explains why he doesn’t like gritty realism.) He lives on in his dying words, carried by wind and rumor and legend to his sons.

Ragnar’s youngest son, Ivar, seeks vengeance against Lagertha for the death of his mother, Aslaug. But his brothers Ubbe and Sigurd pull Ivar’s focus toward on another vengeance. Should they attack King Aelle, in tiny Northumbria — or, following their father’s wishes, take on King Ecbert in grand Wessex? To do so would require a large army, twice the size of the coalition Ragnar led to Paris. But is it an army they can assemble, with their father’s memory as their rallying cry. “In the name of Ragnar Lothbrok, in the name of Odin, we declare war on the whole world,” says Ivar Boneless, hate and joy in his eyes.

Ubbe relays their plan to Queen Lagertha. He asks her to join them. But Lagertha has a reason to stay. The sons of Ragnar are inviting other rulers to her city. “They will see the size and understand the value of this trading station,” says Lagertha. The city has to be defended. “I know what your father would have wanted me to do,” she says. Lagertha remembers when Ragnar was a young man, ambitious like his sons, and remembers one of Ragnar’s great ambitions: to build something that lasts. Lagertha has seen many great men brought low. She saved Kattegat from Aslaug, didn’t she? She will save it from any assault, won’t she?

But can she save herself? Perhaps she doesn’t want to. The seer says she will be killed by a son of Ragnar Lothbrok. Ivar certainly would like the opportunity. His brother, Sigurd, disagrees. “We have different memories of mother,” he says. “She doted on you and she ignored me.” Sigurd baits his brother; he calls him a mama’s boy, and mommy’s little favorite. Ivar lifts his axe to his brother, aiming to kill. Only the ready arm of a humble blacksmith stops him. Will brother kill brother? Can Ragnar’s sons survive Ragnar’s legacy?

NEXT: Home, wherever that is

In Northumbria, King Aelle welcomes unwelcome Judith to the home she never wanted. How far she has come from her father’s hall. Wife of Aethelwulf, lover of her husband’s father, mother to another man’s son. She has a message for her family. “There is much talk of the revenge of the sons of Ragnar,” she says. “I wanted you all to be aware of it and prepared for it.”

Aelle is ready for any incursion, he promises; anyhow, he needs no help from the likes of his daughter and her degenerate lover. Judith’s father condemns her and her mother condemns her. “If we do not pray for your soul, daughter, then you will be damned for all eternity.” Hell would be a fine place, Judith declares. “As for you, Father, you may enjoy the erudities of heaven without my discomforting presence, and that of every other woman whose only crime was a desire to be free.” She advises her sister to learn to read, pays her respects to great Ragnar Lothbrok, and then she is off, away from Northumbria on the road to destiny.

Meanwhile, Duke Rollo returns home from his Mediterranean jaunt with his former allies. His nephew, Bjorn, has told him he will never be welcome back home in the lands of the Northmen. They would want him dead; Bjorn would have to kill him. It is a kindness to leave him in Frankia, and Rollo returns with his own kindness. “I want to make you all an offer,” he says. “Anyone from our homelands who wants good rich lands to farm can come and live in my kingdom. It will always be a part of Frankia, which is a part of us.”

Ironic, or inevitable. This a dream held by Rollo’s brother, Ragnar: to settle far from home, to farm foreign lands. And now it falls to Rollo, the traitor, to bring Ragnar’s dream to life. Floki spits at him. “You are no longer a part of us, Rollo,” he says. “What is us, Floki, is changing,” Rollo claims. “Only you won’t accept it.” So, Rollo leaves his people one more time, promising he will never forget them. His wife, Gisla, greets him at home, with violence and cries and the righteous words of a spouse betrayed. But she does welcome him. “I have a bad feeling,” Floki tells Bjorn Ironside, “that he will reach more fame than any of you.”

NEXT: Betraying the traitors

In Wessex, King Ecbert struggles to educate his grandson, Alfred. He tries to tell him books are just as important as swords or plowshares; he tries to teach him to be clever and to think for himself. But there is power in community, too. In Kattegat, the sons of Ragnar welcome the first arrivals in their vengeance army. These are young Vikings, who think of Ragnar as their own father.

They have heard the poems about Ragnar — and about Lagertha, too. An earl from Sweden greets Lagertha, telling her the songs about her are almost tiresome — the fault of the poets, not of her. “Ragnar and I were simple farmers,” says Lagertha, with a tone of voice suggesting she was never really just a simple farmer.

But Lagertha remembers more modest days. She does not know this Ragnar the young men talk about … the hero, the father. She remembers a man who was hers. She sees his son, Ubbe, who looks at her with such hate. She tells him, “You look just like your father looked when he was a young man, when I first knew him.” She is reaching out to him, or perhaps she is saying: I understand what you are feeling. For she remembers when Ragnar was a young man who felt his family was under attack, and she remembers what Ragnar did to the man doing the attacking, and she knows how few people today remember Earl Haraldson.

The sons strike, Ubbe and Ivar. They have allies; they kill shieldmaidens, close the hall, advance on the Queen. She advances to them, sword in hand. But then there is a homecoming: Bjorn Ironside, back from his quest. He knows his half-brothers want vengeance. But there is a more important vengeance: their father and the land of Christians across the sea.

That is what Bjorn says, in public. In private, perhaps, he feels much different. His mother has her vengeance, and so she is Queen. He sits with his family, with Torvi and his children, and he has never looked less comfortable. “I did not come back here to be told what to do!” he says. “Not by you! Not by anyone!” He stalks out, angry, and goes to the throne room. His mother is gone, but Astrid is there. Astrid looks upset; Lagertha does not tell her everything. So, Astrid and Bjorn have something in common, and perhaps it is that that leads them to kiss each other, or perhaps they want to punish Lagertha, or perhaps they are both a bit mad.

The other sons of Ragnar Lothbrok recede, biding their time. Hvitserk agrees with Sigurd; he has few good memories of his mother and thinks someone ought to rule Kattegat while they set off. Who shall that be? On the outskirts of the city, they are building, building, building, and there is King Harald and his brother and their new friend, Egil, who is not beautiful but very clever. They plot, as ambitious men must plot.

And in the forest, Floki is building, too. He carries little Ivar, his favorite student, and he gives him a present. “Your legs, Ivar,” says Floki, showing Ivar a personal chariot. “Your wings.” And off Ivar goes, the boy with no legs moving faster than any man can run, a smile on his face and murder in his heart.