After returning from Constantinople, Ambrose and his friends ride north with his brother the king to face the all-conquering Great Army of the Vikings. The king of Mercia sues for peace and battle is averted. Fearing a massive surprise attack, Ambrose and his friends ride north as spies and join the Great Army. Recognized, the friends must flee and battle their way back to safety. Ambrose is wounded and only the love of a maiden and friendship of a mysterious trader saves his life. Betrothed, Ambrose rides south to Wessex.