Tensions mount between the sons of Ragnar Lothbrok; with King Aethelwulf and his family still in hiding, Heahmund, the warrior bishop, rallies the Saxons to defend the Realm, as the Great Army moves to take York.
- Katheryn Winnick as Lagertha
- Gustaf Skarsgård as Floki
- Alexander Ludwig as Bjorn
- Peter Franzén as King Harald "Finehair"
- Jasper Pääkkönen as Halfdan "The Black"
- Moe Dunford as Aethelwulf
- Alex Høgh as Ivar
- Marco Ilsø as Hvitserk
- Jordan Patrick Smith as Ubbe
- Jonathan Rhys Meyers as Bishop Heahmund
- Josefin Asplund as Astrid
- Ida Marie Nielsen as Margrethe
- Ferdia Walsh-Peelo as Alfred
- Georgia Hirst as Torvi
- Jennie Jacques as Queen Judith
Additional Cast (in order of appearance)
- Jonathan Delaney Tynan as Lord Cuthred
- Keith McErlean as Lord Denewulf
- Jim Roche as Saxon Scribe
- Darren Cahill as Aethelred
- India Mullen as Aethelgyth
- Jake O'Loughlin as First Saxon Boy
- Ben Smith-Short as Second Saxon Boy
- Frank Prendergast as Bishop Cynebert
- Anna Shiels-McNamee as Young Nun
- Ben Roe as Guthrum
- Bishop Cynebert
- Some digital services billed part one as "The Fisher King" while part two was billed as "The Departed".