Lords of the North (the Last Kingdom Series, Book 3)

Book 3 of the series. After having fulfilled his oath to Alfred by defeating Guthrum and his army at the Battle of Ethandun and thus giving Alfred his kingdom back, Uthred goes back to Northumbria both to settle his score with Kjartan (now known as Kjartan The Cruel) and his son Sven The One-Eyed, and to fulfill his promise to Ragnar The Younger of avenging the death of their family. Ragnar (and Brida), after having fought with Guthrum and lost, are now Alfred’s prisoners in Winchester. But fate decreed that Uthred go first to Cumbraland where he meets Guthred, the slave meant to become the king of Northumbria. Uthred frees him and becomes his friend and man. However, Guthred betrays Uthred and sells him as a slave in exchange for 200 swords from Bebbanburg. Ragnar learns of Uthred’s fate and sets out to look for him on Alfred’s behest.