After the death of Ragnar Lothbrok, the story of this season will revolve around the power struggle between Bjorn, Ivar the Boneless, King Harald Finehair, Lagertha and Ubbe. When the season begins, Ivar the Boneless declares himself the leader of the "Viking Lion" and controls the city of York, while Lagertha rules the Kattegat as queen. Ragnar's sons plan to avenge their father in their own way, but Ivar murders his brother Sigurd in a fierce dispute, triggering a series of bloody civil wars-obviously, the other brothers do not believe Ivar's explanation. Bjorn followed his destiny to the Mediterranean and arrived in Tunisia (on the edge of the Sahara Desert). Rollo returned home from the Mediterranean. He has changed completely, but his relationship with his family and friends is still tense. Floki lost his wife Helga, so he took a boat and drifted on the sea, letting God guide his direction.