It is 878 and Wessex stands alone against Guthrum's Viking hordes as all England cowers beneath their raven banner.
With most of his army destroyed following a surprise attack at Chippenham, Alfred King of Wessex, retreats to the desolate marshes at Athelney. Whilst few believe he can ever restore the kingdom, he remains determined - no matter the cost.
Among the small band of weary survivors is Matthew, a novice monk who must learn to fight like a warrior if he, along with his brother and fellow Saxons, are to have any chance of defeating the Vikings. As the impending battle looms, Matthew is charged with a vital role that means he must face danger and betrayal, and undertake a hazardous journey during which his faith will face the ultimate test.