The peace has broken, the Danes are threatening Wessex, and a huge storm rages. Uhtred puts himself forward for a daring stealth mission to outflank the Danes and destroy their ships, but in the process is challenged to a one-on-one fight with Ubba.

The Danish invasion of Wessex sees Uhtred driven to hiding in the marshlands with King Alfred. With Wessex lost and the life of Alfred's child hanging in the balance, a bond is finally struck between the two men. They must work together if Wessex is to be reclaimed.