Full episode spoilers.
Lagertha buries Kalf and explains to Erlendur that she killed him because she had promised to do so after he took her earldom. He asks to join the expedition to Paris rather than leave Hedeby. In Kattegat, Ragnar gives Ubbe and Hvitserk arm rings and announces that they will travel with him. Aslaug objects to the danger, but Ragnar insists on taking his sons away from her care.
Yidu persuades Ragnar to bring her by reminding him that he depends on what she supplies and saying she speaks Frankish. Before departing, he asks the Seer about his death and receives an answer about a blind man seeing him. The fleet leaves Kattegat, and Harbard returns in Ragnar's absence. In England, Ecbert sends Alfred to Rome with Aethelwulf and prepares to lead the campaign for Mercia himself.
The Vikings reach Francia and attack a riverside position, but an escaping soldier warns Paris. Harald's men burn prisoners, while Ragnar questions Lagertha about risking her pregnancy on the raid. She reminds him that he broke her heart long ago. Erlendur threatens Torvi's child to force her to kill Bjorn. Near the river defences, the Vikings discover that their old camp is gone and see Rollo standing with the Frankish forces, making his allegiance plain.