Uhtred, along with Hild and Iseult, decided to go back to Northumbria where his enemies Sven the One-Eyed and Kjartan are controlling Dunholm and his uncle Ælfric Bebbanburg. But, when they reach Eoferwic (York) they find chaos. Ivarr Ivarsson, a powerful Danish lord, led his army against the Scots leaving Eoferwic weakened, the Saxons uses this opportunity and under the control of Father Hrothweard, they start pursuing the remaining Danes.

Due to the animosities, Uhtred is hired by a Danish merchant to escort his family to the north, through Dunholm. He ends up reaching a slave trade post belonging to Sven, Uhtred hides his face and calls himself Thorkild the Leper, a swordsman from Niflheim. Eventually, the situation goes out of control, and Uhtred manages to convince Sven that he has returned from the dead. Among the slaves that Uhtred finds is Dane Guthred, that claims to be the king of Northumbria.

Being freed by Uhtred, Guthred converts to Christianity and is received as king by the Saxon Abbot Eadred, that believes that Guthred has been blessed by Saint Cuthbert. Uhtred becomes the commander of Guthred’s troops and his advisor. He trains new warriors and repels the attacks from Kjartan. He helps Guthred to take Woferwic while Ivar Ivarsson is busy fighting the Scots, but when marching to Dunholm, Uhtred is betrayed by Guthred that has made a deal with Ælfric, giving Uhtred as a slave to a Danish trader called Sverri.

Uhtred’s life completely changes, now a slave working as a rower on Sverri’s ship, where he meets an Irish warrior called Finan tht becomes a good friend and ally. After two years his fate starts to change when a red ship starts to pursue their ship, eventually, the red ship attacks, and Uhtred discovers that the ship is from his friend Ragnar. Now rescued by Ragnar, Uhtred returns to Wessex and finds out that Hild convinced Alfred to rescue Uhtred, in return she uses Uhtred’s silver to build an abbey and returns to serve Christ.

Uhtred meets a traveling Mercian entertainer and a spy, Offa, that tells him that Guthred, Ivarr, and Ælfric tried to take Dunholm, but all failed. Alfred sends Father Beocca, along with Uhtred, Steappa, and Ragnar to meet Guthred and make peace in Northumbria, but Uhtred suspects that Alfred has other intentions. When they arrive in Guthred’s court, Uhtred discovers that Gisela, Guthred’s sister which whom Uhtred has fallen in love, has been married to Ælfric by proxy in return for support against Kjartan.

Uhtred believes that his uncle has no intention to honor his alliance with Guthred, therefore he would not send any men. He expels Ælfric’s men, and claims that Gisela is not married to Ælfric, Bother Jænberht disagrees and gets killed by Uhtred. Intimidated, Brother Ida agrees that Gisela is not married, as the marriage has not been consummated.

Uhtred forgives Guthred and tells his intention of marrying Gisela, the churchmen request the execution of Uhtred for the killing of Jænberht, but Guthred didn’t listen to them and agrees with the marriage.

Uhtred now becomes the commander of Guthred’s troops to attack Dunholm, he plans to become again a shadow-walker (sceadugengan) and use the darkness in his favor. He chooses eleven of these best men to follow him and climb the hill and use a gate used to get water to sneak into the fortress.

Eventually, they got discovered, but due to the fate of destiny, they are saved by Ragnar’s sister, Thyra, who has fallen into madness after many years held by Sven. Thyra turns the dogs against their master, and this gives Uhtred the chance to open the gate for the rest of the men to enter the fortress. Finan defeats Sven, and Ragnar gets his revenge against Kjartan, killing him but not giving him the chance to hold a sword, denying his entry into Valhalla.

Father Beocca sees Thyra and believes she is possed by demons, and he prays performing a kind of exorcism and Thyra recovers her sanity. Guthred makes Ragnar lord of Dunholm.

There is still one threat left, Ivarr. Both armies meet in the field for a final battle, Uthred provokes and gets into single combat against Ivarr, defeating him.