In the battle for power, there can be only one ruler.

Britain, early tenth century AD: a time of change. There are new raids by the Vikings from Ireland, and turmoil among the Saxons over the leadership of Mercia. A younger generation is taking over.

When Æthelred, the ruler of Mercia, dies, he leaves no legitimate heir. The West Saxons want their king, but Uhtred has long supported Æthelflaed, sister to King Edward of Wessex and widow of Æthelred. Widely loved and respected, Æthelflaed has all the makings of a leader—but can Saxon warriors ever accept a woman as their ruler? The stage is set for rivals to fight for the empty throne.

Uhtred is still suffering from wounds he received in battle. To recover his strength he needs to find the sword that caused the injury, but, lost amid the battle's blood and mud, how can it be traced, and who among the Vikings or Saxons may be holding it?

In the end it is one champion, one hero, who will destroy the new Viking threat to Mercia—and ultimately decide the fate of England.