From back of book: To the North of the Holy Roman Empire lie the pagan Norse-lands. It is here that Manfred, Prince of Brittany, and his Icelandic bodyguard, Erik, must venture in the dead of winter, to a rugged land of trolls and ice. Their quest: to find a pagan relic, something so magical that it should not be possible to touch it, let alone steal it. Yet, it is gone. Unless it is recovered before Yuletide, a new Viking age will be born. King Vortenbras will lead his berserks in an orgy of rapine, looing and destruction across the Empire's unguarded flank.

Princess Signey is the King's older stepsister. Everyone believes her to be the thief, a witch and murderess. Everyone but Cair, her stable-thrall, a captured pirate with a hidden past. Cair doesn't believe in witches or magic, let alone that Signy could steal and murder. And if he has to drag the foremost knight of the age and his bodygruard kicking and screaming through the entire Norse underworld to prove it, he'll do it. Cair's a man of science, and he's used that to fake his way into being feared as a magic-worker. But for Signy, he'll be all of mankind's witches. He'll have to be Because that's what it'll take to defeat the dark magics massed against her.

(Source: Baen)