In the first episode of this season, we see Bjorn arrest Floki for the dead of Athelstan. When his father isn't too pleased about this when he woke up Bjorn learns a valuable lesson from that. Ragnar still thinks he is stupid and when he ask to go away by his own into the wilderness he didn't get much of approval either. Ragnar agrees with his decision but fears the worst. When Bjorn is in the wilderness we see him almost freeze to dead before arriving at the cabin. As he went out for fishing he sees a bear. When he finally approach the bear he realizes that he has forgotten his axe. After he has set traps to hunt a bear down he kills the bear.
Kalf and Erlendur plot a plan because Erlendur wants Bjorn dead, to revenge the dead of his father King Horik they sent a berserker his way. With the ring of King Horik to get him passage through the different kingdoms. How foolish of Erlendur it was to do that. After Bjorn get into the fight with the berserker and tortured the men he is given the ring.
Bjorn gets to Hedeby before Yule he gets Torvi away from Erlendur. Torvi needs to leave her child behind. Lagertha tells him there is still time to get to Kattegat to celebrate Yule. He spends Yule at his father's place in Kattegat. Bjorn isn't too pleased to see Aslaug and King Finehair especially when he hears what King Finehair wants. Ragnar comes in and tells
Bjorn he isn't pleased to see Torvi in Kattegat.
Torvi sees the ring when Bjorn is looking at it and tells Bjorn it is from Erlendur. Bjorn confronts Erlendur with the ring he is lying to Bjorn that he have never seen the ring. Ragnar, however, doesn't trust King Finehair something he has in common with Bjorn. Bjorn goes and talks to King Finehair. He has nothing to fear from King Finehair.
The first defeat in Paris is a fact and Bjorn talks to his father that he needs to do something about the defeat because of the family name. When they strike the second time we see Bjorn already much more in his role of becoming a leader. When his mother get's wounded he carries her into the boat and gets Ragnar by someone else in the boat as well to sail away back to Kattegat.
If Aslaug gets Bjorn away from the fishing we see an irritation towards Aslaug. When he finds out why she called him he isn't too pleased to hear the story about Magnus and gets really angry to hear from the Wessex settlement that it has slaughtered. He doesn't know because it was never told to him. It is then that we hear Ragnar is gone for so long as they arrived back in Kattegat to nowhere be found.
After Aslaug told him were his brothers are because they need to know we see Bjorn up at the cabin where we meet the grown-up versions of Ubbe, Hvitserk, Sigurd, and Ivar. They want to spread the news about Magnus and the settlement because if Ragnar is coming back two of them want him dead. Ivar, Ubbe, and Bjorn don't want to know they took it and defend Ragnar. Bjorn tells them although Ragnar has failings and was almost a god to a lot of people he is still a man in Bjorn his eyes. Ivar and Ubbe want to know more about Ragnar mind and strategy.
We see Bjorn at Floki who knew about the settlement and we see boats. Bjorn wants to sail the Mediterranean sea. Imaginary land on a map according to Floki but when Bjorn asks him to come he comes.