In the seventeenth century, in an alternate universe where Mordred defeated King Arthur-now known as "Arthur the Tyrant"-and founded the Pendragon dynasty, much of Europe, Asia, and the New World are part of an Empire ruled from England. The Order of Crown, Shield, and Dragon, originally founded as Mordred's personal bodyguard, has become a legion of special agents for the Crown: special emissaries in time of peace, and invincible warriors in more violent times. They carry special weapons: swords, each of which contains the soul of someone of great power. White swords are inhabited by the souls of saints-and red swords by those who were anything but saints. Even in the hands of a knight of the Order, even wielded in the cause of righteousness, a red sword is terribly dangerous to its owner and all around him. In more evil hands, a red sword is the most dangerous and powerful weapon known to mankind. Now, three knights of the Order have just tracked down a previously unknown red sword which was found on a Grecian shore, and which shows all signs of having been recently forged. Worse, the mind encased in the sword remembers that it was only one of many which were cached in the hold of a mysterious sailing ship, origin unknown...

In a seventeenth-century alternate universe in which Mordred had defeated King Arthur, establishing a dynasty that rules much of the world, the Knights of the Order of Crown, Shield, and Dragon are faced with the return of an ancient witch, a swarm of darklings infesting all Europe, and a deadly being that has infected the inhabitants of Colonsay with a murderous frenzy.