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.

Three years have passed. Uhtred has an estate in Wessex with Gisela and their two children. He receives a visit from Aethelwold, who tells him that a medium, Eilaf, has prophesied that he will replace Alfred as king of Wessex and Uhtred will become king of Mercia. Knowing that Alfred despises his brother's weakness Uhtred does not tell the king the whole story but also learns that Alfred means to marry his daughter Aethelflaed to young lord Aethelred of Mercia to provide an alliance. Another alliance is proposed when Erik returns, seeking Uhtred's cooperation in an attack on London. Instead Uhtred visits Eilaf, who tells him that one day he will be the ruler of all the kingdoms in England.

Alfred's daughter Aethelflaed is married to the arrogant, scheming Mercian lord Aethelraed, for whom both Uhtred and Aethelwold have nothing but disdain. Aethelraed is also a bullying husband, casting doubt on his wife's fidelity, but he manages to secure influence with the king by persuading him that Uhtred is not to be trusted. After failing to buy off Erik and Sigefrid following their capture of London Aethelraed and Uhtred join forces to lead a liberating army but find the city strangely empty. This is because, unknown to them, the Danish brothers have a more lethal plan of their own.

Tricked into abandoning their camp for an abortive attack on London the Saxons and Uhtred return to find it a scene of massacre with Thyra, now married to Beocca, among the few survivors and Aethelflaed captured by the Danes and taken to East Anglia as a hostage. Alfred is furious with Aethelred, to Aethelwold's delight, and sends him to negotiate her release . At the suggestion of Odda and Aethelwold, Uhtred accompanies him. However Aethelflaed finds captor Erik far more tender towards her than her brutal husband, who is richly humiliated by the Danes and she lets Uhtred know she has no desire to return to Wessex.

Uhtred returns to Alfred, keeping Aethelflaed's secret and allowing the king to believe he can ransom his daughter, setting him at odds with Odda and Aethelwold, who propose a military intervention. To his brother's annoyance Erik declares his public love for his captive but in reality he plans to keep both her and the ransom and it is Uhtred who exposes the plan, effecting his own rescue and gaining the thanks of both the princess and her father - though Alfred still does not wholly trust him.