Uhtred puts himself forward for a daring stealth mission to outflank the Danes and destroy their ships, but in the process he attracts Ubba's attention and is challenged to a one-on-one fight to the death.

Uhtred and Leofric must face off against each other in a death match-a consequence of their actions in Cornwall. But there are ominous signs of a greater battle to come - The Danes launch an invasion on Wessex, pouring through the streets and killing all in their path. Running for their lives in an escape to find safety, a bond is finally struck between Uhtred and King Alfred; the two men recognize they must now stand and fight together if Wessex is to be reclaimed. Uhtred realizes that his best chance of regaining Bebbanburg rests on Alfred's return to the throne.

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.

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.

King Alfred's health is failing. As time runs out for him to unite the kingdoms of England, his greatest warrior Uhtred must lead Wessex in battle against the fearsome Bloodhair. When Uhtred is cursed by vicious seer Skade, tragedy follows.

When Uhtred commits a serious crime Alfred turns events to his advantage but is outraged when Uhtred retaliates with an act of violence. Uhtred must embark on a voyage and Skade's power takes hold - has he passed a place of no return?

A deadly betrayal threatens to splinter Ragnar's army. Uhtred forms a cunning battle plan and finds an unexpected ally in young Edward.

Edward makes a kingly decision. Alfred lays plans for his son's future reign. Aethelwold faces a treacherous task. Uhtred and Brida search out a seer.

A message from Uhtred and the machinations of Skade exploit divisions among the Danes. His health failing, Alfred wrestles with Aethelwold's fate.

Uhtred risks returning to Wessex to fulfil his vow to Brida. As the royal wedding approaches, Aethelwold spreads discord from the shadows.

At the end of his days, Alfred takes Uhtred into his confidence about his plans for Edward's uncertain future, but Aelswith charts a different course.

As a huge battle with the Danes is close, Edward has to make pivotal decisions that will affect the fates of Uhtred, Wessex - and England.

Uhtred receives news that Bebbanburg's defences have been weakened by Scottish attacks and plans to seize his birthright, but Edward refuses to help.

As Uhtred and his men draw closer to Bebbanburg, the prodigal son Wihtgar returns with some tricks up his sleeves. News of a treachery troubles Uhtred.

As he lingers near death, Aethelred shows repentance. Ealdormen of Mercia vie for control of the land. Edward uses his niece Aelfwynn as a bargaining chip.

Eardwulf and his men pursue Uhtred's party as it flees through a countryside ravaged by disease. Tensions between Edward and the Mercians rise.

Aelfwynn suffers from the sickness sweeping the land. Edward proposes an unexpected path forward for Mercia. Cnut's kinsman Sigtryggr arrives in Wales.

Uhtred reluctantly prepares to take power in Mercia but he has an alternate plan in his mind. Brida joins the Danes in attacking the Welsh.

Brida and Sigtrggr lead the Danes to Winchester, guided by the traitor Eardwulf. Haesten ambushes Uhtred's party and seizes valuable captives.