In season four of The Last Kingdom, Uhtred finally moves forward with his plans to take out his
villainous Uncle Aelfric and reclaim his rightful home of Bebbanburg. He attacks with a small group,
including his friend Beocca and son, Young Uhtred. But it turns out, Uhtred’s just a little too late,
as Aelfric’s son Wihtgar has also arrived to take control for himself. Wihtgar kills his father and
the men of Bebbanburg pledge to him their loyalty. They then turn their focus on Uhtred and his men.
Beocca sacrifices himself to save Young Uhtred, as the others flee from Bebbanburg. Young Uhtred,
who resents his father’s violent, Pagan ways, decides to become a cleric of the Christian
church. Uhtred disavows his son, taking back his name. And so, Young Uhtred becomes Bishop Oswald.
Meanwhile, Aethelred conspires with his army commander Eardwulf on how to heighten the power of
Mercia to equal that of Wessex. Eardwulf’s family name had been tarnished, but Aethelred promised to
restore it to its former glory if Eardwulf helps him conquer all of East Anglia. As they begin
fighting to reclaim Viking land in East Anglia, Cnut, Brida and their army take the opportunity to
invade Mercia. Aethelflaed races to rally Mercian troops to fight back the Danish army. Edward
is persuaded by his shady new advisor and father-in-law Aethelhelm to hold back on sending
forces, as a defeat in Mercia could rid them of the nuisance that Aethelred had become. Edward’s
mother, Aelswith, has different thoughts on the matter, wanting to not only protect her daughter,
Aethelflaed, but ensure that Edward would still retain the loyalty of the Mercian people. And so,
Aelswith goes behind Edward’s back to ask the Welsh King Hywel for his assistance. Meanwhile,
Uhtred rushes to be by Aethelflaed’s side and along the way he encounters the Viking Haesten,
who was looking after Cnut’s sons. Haesten reveals to Uhtred Cnut’s involvement in Ragnar’s death.
Uhtred kidnaps Cnut’s sons and joins Aethelflaed in the Mercian village Tettenhall. As the Danes
attack, the Mercian and Welsh armies defend their land. Soon, Aethelred arrives with his army,
as does Edward with the Wessex army. With the combined Christian forces,
the Danish army is finally defeated. During the battle, Uhtred and Cnut fight, and a pregnant
Brida learns of Cnut’s involvement in Ragnar’s death. So she takes her revenge, killing Cnut,
the father of her unborn child. As the battle dies down, Brida asks Uhtred to kill her and
send her to Valhalla, but Uhtred refuses and Brida is captured by the Welsh and made a slave.
During the battle, Aethelred is mortally wounded. On his deathbed,
he must help find a suitable husband for his and Aelthelflaed’s daughter, Aelfwynn,
to ensure their succession of the crown. Eardwulf befriends Edward, who then proposes Eardwulf would
make a perfect match. When Aethelred rejects this idea, Eardwulf kills him. Aethelflaed
also rejects this proposal, so Edward has her imprisoned until after the wedding. Uhtred flees
with Aelfwynn and discovers that Eardwulf had murdered Aethelred. When Uhtred tells
Edward this revelation, the King realizes the error of his ways and dismisses the treacherous
Aethelhelm as his advisor. Edward recognizes the loyalty and respect Uhtred has over the Mercians
and decides to appoint him Lord and Protector of Mercia until a suitable match can be found for
Aelfwynn. Uhtred’s first act on the throne is to immediately relinquish the power to Aethelflaed.
Aethelflaed is made Queen of Mercia until Aelfwynn marries, and takes a vow of chastity to ensure the
succession passes to her daughter. This move at first infuriates Edward, but he realizes he needed
to stay aligned with his sister and Mercia to keep their kingdom under Saxon control.
Meanwhile, the Viking warlord Sigtryggr raids the Welsh settlements and frees Brida. As they
continue to decimate the Welsh army, they come across and capture Eardwulf, who was in hiding
following his murder of Aethelred. Eardwulf tells them that Edward had left Winchester undefended,
so the Viking army turn their attention there. The Danes take control of Winchester and imprison many
of its inhabitants, including Aelswith, Aethelhelm, Aelflaed, Edward’s children
and Uhtred’s daughter Stiorra. When Eardwulf assaults Stiorra, Sigtryggr has him killed.
Uhtred leads a negotiation with Sigtryggr to come to a truce. Sigtryggr is given the Northumbrian
capital of Eoferwic in exchange for his surrender of Winchester. Sigtryggr also takes a willing
Stiorra as a captive to ensure the truce’s legitimacy. As the truce between the Saxons
and Danes is established and the season comes to a close, Brida vows to be Uhtred’s undoing,
Aethelhelm poisons Aelswith, and Edward entrusts his son Aethelstan into Uhtred’s care.