May 1941. The Blitz is reaching its fiery climax. Christopher tries to go back to 1666; to find his new friends and learn more about the power of his phoenix ring. Instead, he finds himself in a smaller, older river port town known as Lundenwic, where the Anglo-Saxon community faces an invasion by the dreaded Vikings. Christopher must discover why the ring has brought him here, and how to get back to his own time. But then Viking ships appear on the Thames, and their warriors threaten to burn the city and conquer the whole of England.