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.

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?

Bloodhair and Athelwold try to coax Uhtred into their alliance against Alfred. Fearing for her life, Aethelflaed turns to Father Beocca for aid.

Uhtred turns his attention to Aethelflaed's plight. Alfred forces Edward to face his duty. Ragnar's army marches but traitors emerge from within.

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.

Uhtred suffers a great loss on his attack on Bebbanburg. As he retreats south, he takes some valuable captives. Aethelflaed prepares for war.

Aethelflaed and Uhtred ally with the Welsh king Hywel to face Cnut's army of a thousand warriors at the Battle of Tettenhall, hoping that they will be joined by Edward's troops.

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.

As he awaits Aethelflaed's reinforcements, Edward besieges Winchester. Uhtred isn't convinced that conquest is really Sigtryggr's ultimate aim. Stiorra seeks to follow her own path. The wind shifts in Winchester.

Ill omens and border raids make Uhtred extra vigilant at his northern outpost. King Sigtryggr is visited by his notorious brother Rognvaldr.

A betrayal at Eoferwic sends Sigtryggr in search of aid, while Uhtred begs Aethelflaed for military support she cannot give. Edward meets a new ally.

In the aftermath of the tragic battle for Eoferwic, Sigtryggr is forced to make a painful choice. Edward learns of Aethelhelm's intrigues in Mercia.

Rivals secretly advance competing successors upon the death of a Mercian ruler. Brida finds solace in the faith of her prisoner, Father Pyrlig.

Aethelhelm's subterfuge successfully foments war tensions between Edward and Sigtryggr, but his thugs make a crucial mistake in attacking a pilgrimage.

The forces of Edward and Sigtryggr march toward battle as Uhtred races to reveal the truth of Aethelhelm's scheming and avert a ruinous war.

Edward offers a role to Stiorra that would restore her to power. Aethelhelm meets with a Saxon enemy. Uhtred has a long-overdue reckoning with Brida.

Upon learning of Aethelhelm's location, Uhtred proposes an audacious attack to rescue Aelfwynn and restore his birthright - but Edward is cautious.

Edward marches his troops north while Uhtred recruits a small force to infiltrate Bebbanburg. King Constantin arrives to meet his new bride, Aelfwynn.

Armies converge in an epic, final showdown that determines the fate of a king's dream for England - and Uhtred's hope for securing his family's future.

Uhtred suffers a great loss on his attack on Bebbanburg. As he retreats south, he takes some valuable captives. Aethelflaed prepares for war.

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

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?

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

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.

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

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

As he awaits Aethelflaed's reinforcements, Edward besieges Winchester. Uhtred isn't convinced that conquest is really Sigtryggr's ultimate aim. Stiorra seeks to follow her own path. The wind shifts in Winchester.

Bloodhair and Athelwold try to coax Uhtred into their alliance against Alfred. Fearing for her life, Aethelflaed turns to Father Beocca for aid.

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