Season five begins with Ivar the Boneless asserting his leadership over the Great Heathen Army, while Lagertha reigns as Queen of Kattegat. Ivar's murder of his brother Sigurd sets the stage for vicious battles to come as Ragnar's sons plot their next moves after avenging their father's death. Bjorn follows his destiny into the Mediterranean Sea and Floki who is suffering from the loss of his wife Helga, takes to the seas submitting himself to the will of the Gods. This season is full of startling alliances and unbelievable betrayals as the Vikings fight to rule the world.

Vikings returns for a gripping fourth season. Season 3 culminated with the extraordinary battle in Paris, where Ragnar seized victory from the jaws of defeat–but still returns to Kattegat dangerously ill. Thoughts of his death galvanize the forces who seek to succeed him as king, including his wife Queen Aslaug and his oldest son, Bjorn. Meanwhile, Lagertha continues power struggles with her calculating, former second in command, Kalf; Rollo betrays his Vikings heritage by remaining in Frankia and Floki is seized for his brutal actions to the Christian priest Athelstan.