Full spoilers for this episode.
Floki brings Ragnar's challenge to Earl Haraldson, who first rejects the idea of fighting someone he calls a criminal. He changes his mind and agrees to single combat. Lagertha urges Ragnar to leave rather than fight while his wounds are still healing, but he refuses. In private, Haraldson admits to Siggy that he respects Ragnar's ambition and knows he was right about the west, although acknowledging that publicly would have weakened his own position.
Ragnar wins the duel and kills Haraldson, becoming Earl as the gathered men acclaim him. Siggy kills Thyri's husband, ending the marriage Haraldson arranged. Ragnar receives pledges from his followers, including Rollo, whose oath comes with a pointed condition about his brother's good fortune. He also agrees to take the elderly warrior Tostig on a future raid. Rollo's desire for equal standing remains even as Ragnar takes the authority both brothers once served.
Ragnar grants Haraldson an elaborate funeral. Athelstan watches the preparations with growing horror as a slave woman is chosen to die with the former Earl, and the funeral boat is burned. These are the drama's religious rites, encountered through the captive monk's discomfort. Lagertha tells Ragnar that she is pregnant again. After the seasons pass, Ragnar's larger fleet returns toward Northumbria, where Aelle has an officer thrown into a snake pit and prepares to fight the raiders.