Plot

The traditional pilgrimage to Uppsala to thank the gods brings a torrent of emotions for Ragnar, Lagertha, and Athelstan.

Ragnar, his family and others travel to Uppsala to pay homage to the gods. It's a trip they make every nine years and he invites Athelstan to accompany them. Ragnar is still having difficulty accepting the loss of their baby and Lagertha worries if she will ever bear him another son. The drug, sex and alcohol-fueled festivities are a revelation to Athelstan who learns that there will also be animal and human sacrifice. He renounces his Christian faith but a priest tells him he is to be a sacrificed. He is spared but Ragnar's group must provide a substitute. King Horik welcomes Ragnar who pledges his fealty and his service. In return, he asks Horik to join forces with him so they can send bigger raiding parties to the west. Horik agrees but has a task for him.—garykmcd

Ragnar regrets his wife Lagertha's miscarriage enough, dead-set on a second son, to revert his intent to miss out of his earldom's nine-yearly pilgrimage to the Asen festival at the great Viking temple in Uppsala. So all the Lothbroks go, with several other villagers, to bring bloody sacrifices. Athelstan comes too, bewildered that the ninefold offerings of each species includes male human volunteers. That honor also fell on him, but the pagan priests realize the former monk hasn't sincerely sworn off Christianity, hence is found unfit, to has and cunning Ragnar's relief. Also attending is king Horik, a ruthless schemer who killed off six brothers in turn. He eagerly meets Ragnar, accepts his pledge of loyalty, commends his intent to extend the Western raids beyond Engalnd, to the Frankish realm only Athelstan ever visited, and entrusts ambitious Ragnar with a daring mission to appease the king's territorial rival, another jarl (earl). Widow Siggy warns sexually fickle Rollo not to let his brother monopolize the glory in royal favor.—KGF Vissers

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 Aesir and Vanir. Ragnar says that the ruler of Kattegat attends Uppsala once every 9 years to give thanks for all that the Gods do for them and to offer them sacrifices. Somewhere deep inside, Ragnar believes that Lagertha suffered a miscarriage, and he was no planning to visit Uppsala that year as there was too much to do around Kattegat.

Athelstan agrees to accompany Ragnar to Uppsala. Athelstan finds that his sacred gospel, the only thing he brought from Northumbria, is now rotting and falling apart.

At Uppsala, Lagertha prays for a son to Odin. Ragnar prays for a son and wants to know who would bear him a son. Athelstan finds that sacrifices are made to the Gods at the end of the festival and includes 9 of every kind of animal, including man. King Horik is himself schedule to attend the festival at Uppsala.

Rollo introduces Athelstan to some natural mushrooms that have a drugs like effect on humans. Athelstan then participates in an orgy of humans at Uppsala. He finds Thyri, who kisses him and brings him into her tent to bathe him. Athelstan asks why she does this, although she only responds that she "must."

King Horik arrives at Uppsala the following morning. Ragnar pledges fealty to King Horik (Donal Logue). Ragnar says that he recognizes Horik as a just and progressive ruler and says that he is not satisfied by what he has achieved so far. Ragnar says that he wants to send bigger raiding parties to the West and bring back bigger riches. Ragnar introduces Athelstan to Horik to talks about new lands such as Francia, with far greater riches. Horik charges Ragnar with an embassy to Jarl Borg (Thorbjorn Harr), a rival encroaching on Horik's lands. Horik wants Ragnar to represent him in Borg's court and argue his case.

Athelstan notices that there are 8 humans already identified for the sacrifice and they are being held in a pen. The Seer takes him to the temple, where Athelstan is told by the priest that he is the 9th human sacrifice.

Siggy chides Rollo for not paying attention to his own advancement and sleeping with other women. Rollo says that he is who he is and says that he will not change for anyone and says that Siggy can leave if she wants to. Rollo says that one day he will be a great man and Siggy will regret leaving him just because he sleeps with other women. Siggy informs Rollo that Ragnar already met Horik and did not even invite Rollo to it.

Priests of Uppsala question Athelstan, now in Norse garb, about his faith. Athelstan denies Christ three times. They discern that despite his claims, he has not renounced Christianity, and they declare him unfit to be sacrificed to the gods.

If the sacrifice is incomplete, the Gods will punish everyone and withdraw their protection. Leif, Ragnar's follower, volunteers in Athelstan's place for this single honor and is sacrificed by King Horik at the climax of the rite together with eight other men and numerous animals.