Ragnar and his brother, Rollo, return from a battle in the Baltic lands during which Ragnar has visions of the god Odin and his valkyries. Home again, Ragnar takes his son Bjorn to Kattegat, for Bjorn's rite of passage. Left at home, Ragnar's wife Lagertha quickly dispatches two would-be rapists. While in Kattegat, Ragnar convinces Rollo that raids to the West are worthwhile and possible, thanks to new navigational tools, but is rebuked by his ruler, Earl Haraldson, who continues to order raids
After gathering volunteers, Ragnar, Rollo, and Floki embark on an unauthorised raid to the west. Lagertha violently objects to Ragnar's refusal to take her along. Earl Haraldson has the blacksmith who forged Ragnar's anchor killed. At sea the crew are caught in a storm, which a manic Floki interprets as Thor proving his ship unsinkable. On land, monks see the ominous sign of a cloud shaped like a dragon. After a tense voyage, Ragnar's men land on the coast of England, near the monastery of Lindi
Ragnar's warband returns in triumph to Kattegat, where the Earl immediately confiscates the plundered riches except for one piece per man. Ragnar picks the distraught Athelstan and returns home. The monk's faith and his vow of chastity perplex Ragnar, but he, nonetheless, gathers useful intelligence about the kingdom of Northumbria. Based on this new insight, Earl Haraldson authorises another raid on England. Now accompanied by Lagertha and the Earl's brother, Knut, Ragnar re-embarks post-haste,
The Vikings raid the Northumbrian village of Hexham with little bloodshed, as the villagers are gathered for Mass. During the raid, Lagertha kills Knut when he tries to rape a Saxon villager, and then her. Back on the beach, the raiders defeat a superior Northumbrian force under Lord Wigea, sent by King Aelle, and return to Kattegat. There, Earl Haraldson has Ragnar, who claims to have killed Knut, arrested and tried at the Thing assembly. The Earl's ploy to bribe Rollo to testify against Ragnar
When Earl Haraldson's raiders assault Ragnar's settlement, Ragnar, Lagertha, Athelstan, and the children narrowly escape in a boat. Ragnar is severely wounded, and Athelstan saves him from drowning. The family hides in Floki's house, where the shipwright and his lover Helga slowly nurse Ragnar back to health. Meanwhile, Earl Haraldson marries off his daughter, Thyri, to an elderly earl from Svealand, against his wife, Siggy's, wishes. Aware that the Earl is watching Ragnar's friends, Rollo offer
The Earl accepts Ragnar's challenge, and the two meet in single combat. Ragnar kills Haraldson and Siggy kills Bjarni. After Ragnar becomes the new Earl, he grants his dead foe a chieftain's burial at sea, and Athelstan is revolted to see a slave agree to follow her master in death. During the following winter, Lagertha becomes pregnant and Siggy wants to leave town. But Rollo tries to convince Siggy to stay, asking her to marry him, as he mentions his desire to become an Earl. Athelstan asks Ra
The Vikings set up a fortified camp, assault the Northumbrian besiegers at night, and capture the king's brother, Aethelwulf. In a meeting with the king, Ragnar demands 2,000 pounds of gold and silver as a price for the Vikings' departure. Aelle agrees but demands that one Viking be baptised a Christian, and to Floki's scorn, Rollo agrees. Instead of paying the ransom, Aelle has his men attack Ragnar's camp, but they are bloodily repelled, ending with Rollo finishing off several Saxons single-ha
As Lagertha is unable to conceive another son, Ragnar takes his family and followers to the temple at Uppsala to attend a great rite to the Æsir and Vanir. He pledges fealty to King Horik, who charges Ragnar with an embassy to Jarl Borg, a rival encroaching on Horik's lands. Siggy chides Rollo for not paying attention to his own advancement and sleeping with other women. Priests question Athelstan, now in norse garb, about his faith. Athelstan denies Christ three times. They discern that despite
Ragnar's embassy to Jarl Borg in Götaland fails, as King Horik rejects a compromise settlement about the contested land. Driven by ambition and jealousy, Rollo agrees to support Borg against Ragnar. In Kattegat, a disease kills many inhabitants, including Lagertha's daughter, Gyda, and Siggy's daughter, Thyri. Lagertha asks the seer about Ragnar and her future but the seer refuses as he only sees misery. Underway, Ragnar meets and is seduced by the princess Aslaug; eventually, she reveals she ca