The battle begins between Ragnar and King Horik’s forces against Jarl Borg. Borg is joined by Rollo, and this Viking clash pits brother against brother. There can only be one victor. Meanwhile, Princess Aslaug makes her way to Kattegat and brings with her a surprise that leaves Ragnar in a difficult predicament.
Four peaceful years have since passed with Ragnar as Earl. The time has come for an unlikely alliance to band together in pursuit of a common goal–a new raid on England. A storm pushes the Viking fleet to a new destination, and on the beaches of Wessex, Ragnar and his men may have met their match.
The Wessex Viking raid is in full swing and King Ecbert finds himself facing an entirely new kind of foe. While Ragnar races to dominate in the West, Jarl Borg has his own plans in store for the future of Kattegat.
Ragnar and Ecbert come face to face; Jarl Borg rules Kattegat with an iron fist; Rollo must now become the leader his people need in Ragnar's absence.
Lagertha and Ragnar unite to try to win Kattegat back from Jarl Borg; Aslaug must face the truth of her prophecies; Athelstan struggles to define his faith; Bjorn must once again make a choice.
King Horik returns to Kattegat with a surprising proposition for Ragnar; Lagertha runs into a less than enthusiastic homecoming from her new husband; Athelstan becomes confidant to King Ecbert.
Ragnar and King Horik clash over how to dispense justice to Jarl Borg; King Aelle in Wessex; Ecbert has an eye on a new alliance.
Princess Aslaug's latest prophecy comes to fruition as she readies to give birth once more; Ragnar and Horik have very different ideas about the true purpose of their trip to Wessex.