Having helped Alfred defeat the Danes in Wessex Uhtred is anxious to return to Bebbanburg and reclaim his kingdom. Accompanied by feisty nun Hild he arrives in York where Beocca and Father Hreothward lead the fight against renegade brothers Erik and Siegfrid and aim to free local lord Guthred from Uhtred's old foe Kjartan with Alfred's blessing. Guthred is saved and vows to help Uhtred arrest Kjartan and the treacherous Aelfric though Kjartan escapes. Grateful Abbot Eadred canonizes Guthred but Uhtred's enemies are still plotting to defeat him. Meanwhile in Essex, Brida and Ragnar argue with Alfred over the next way forward.

Uhtred proves his worth to a grateful Guthred and when a group of horsemen arrives, claiming loyalty to Guthred but in reality sent by Kjartan. Uhtred is quick to see through their lies and all are swiftly dispatched, except one Sihtric, who agrees to change sides. Beocca leaves to return to Wessex but the baleful Eadred, still illogically mistrustful of Uhtred, and anxious for a peace treaty with Erik and Siegfrid. poisons the simple gullible Guthred against his former saviour, particularly in the light of Uhtred's fondness for Guthred's sister Gisela. As a result Guthred, anxious for a truce with the Danes, betrays Uhtred, handing him over to his enemies. Beocca seeks Alfred's help in freeing him with Alfred asking Ragnar to locate him before he is taken overseas.

Uhtred is a galley slave on a Viking ship but Aelfric is angry that Guthred did not kill him and breaks the alliance, joining with Erik and Sigefrid to take Durham with savage violence. To appease Aelfric Guthred offers his sister Gisela in marriage but Gisela, in love with Uhtred, refuses and goes into hiding. In Wessex Alfred arranges the marriage of his daughter Aethelflaed to the young king of Mercia Aethelred and sends Hild and Ragnar to rescue Uhtred, which they accomplish when the ship comes ashore to winter. Uhtred is reunited with Gisela but Alfred holds the rescue and the killing of the odious Eadred over him to force him back into the king's service.

Married by Beocca to Gisela, Uhtred joins Ragnar and Alfred's nephew, the reluctant Aethelwold, and others including Hild and Beocca to travel north and defeat Sigefrid and Erik - and ultimately Kjarten, meeting up with Brida on the way. An early victory sends the treacherous brothers into exile and later brings Uhtred's party to visit a contrite Guthred, who now approves the storming of Durham, and release of Ragnar's sister, Thyra. The town is successfully captured and Ragnar faces Kjartan in single combat, a victory for justice, though Thyra does not react as hoped.