Spoilers for this episode.
The victory in Mercia gives way to a feast and competing attempts to hold power. Kwenthrith welcomes Burgred back after insisting that he be spared, then poisons him in front of the assembled rulers. His death leaves her as the surviving claimant to Mercia. The reconciliation she arranged becomes a public killing, and Ragnar and Ecbert watch the woman they have supported remove her own brother.
Ecbert tries to persuade Lagertha to remain in Wessex, but she sees his affection as another way of securing her loyalty. She chooses to return with Ragnar. Athelstan also refuses to stay, despite his growing attachment to Judith and Ecbert's attempt to use that relationship. Porunn struggles with the wound that has disfigured her face, while Bjorn insists that his feelings for her have not changed after the battle.
In Kattegat, Aslaug sleeps with Harbard while Siggy continues watching Ragnar's sons. Ubbe and Hvitserk wander onto a frozen lake and fall through the ice. Siggy jumps in and brings the boys back toward the surface, but does not save herself. During the rescue she sees her dead daughter, Thyri. Harbard appears at the water, and the children survive while Siggy sinks. Ragnar's sons are brought back alive, but the woman who followed them into danger has drowned before the fleet returns.