Norsemen sail across the Channel into the realm of the great Frankish emperor and confront a massive Crusader force. Aboard a dragon ship an English monk guards a book wrapped in cloth whose true worth is known only to him. At their leader's side is Raven, with a blood spot in his eye and magic in his soul, and he and Cynethryth, the runaway daughter of an English king, plunge into an epic clash of men and faiths.

Princess Natasia is the eldest child of Emperor Andreth of the Four Realms, but as a girl she is expected to marry so her father can shape a male successor. An unknown would-be assassin nearly takes her life, revealing that someone seeks to destabilize the Empire, with suspects including Western lords, eastern barbarians, or the mysterious Cult of Culo. With palace intrigue growing dangerous, the Emperor considers Natasia as a possible heir and the reckless, rebellious princess must learn to lead before the Empire falls.