878 – 880/881: Angered by Alfred's meagre reward for saving his kingdom, the 21-year-old Uhtred of Bebbanburg sails back to his native Northumbria in 878, seeking revenge against his uncle Ælfric and childhood enemies Sven the One-Eyed and Kjartan the Cruel.

Ivarr Ivarsson, the most powerful Danish lord in Northumbria, has led his army north against the Scots.

Their path leads to a trap laid by Sven to capture and either sell travelers into slavery or extract ransoms from them.

In order to avoid being recognised, Uhtred hides his face and calls himself Thorkild the Leper, Dark Swordsman of Niflheim.

He trains a band of thirty new warriors and foils an attempt by Kjartan's infiltrators to capture him and Guthred.

During a trading venture to England in the year 880, 23-year-old Uhtred is confronted by Sven, who recognizes him but is scared away when the red ship appears, and warriors debark and attack.

Upon meeting with a Mercian traveling entertainer and spy, Offa, Uhtred learns that Guthred, Ivarr and Ælfric besieged Kjartan at Dunholm, but failed.

In the night, he and eleven of his best men climb the hill and sneak into the fort through a gate used to fetch well water.

Although they are discovered, they are assisted by Ragnar's sister Thyra, who has been held by Sven and Kjartan since the events of The Last Kingdom.

Kjartan himself is killed in single combat by Ragnar, who refuses to allow him to die with a sword in his hand, thus denying him entry into Valhalla.