Thirteen generations ago, the ambitious first Duke of Magnussen made a fell pact with an unknown power, who asked for but one thing in return: the thirteenth daughter born to a Magnussen duke. Now, generations hence, the daughter of Duke Magnussen XIII is stolen away by a hooded executioner riding a leathery beast. As it wings back across the city walls to drop behind the Duke's mountain-top keep, all who watch know it alights in the Magnussen family crypts, where the devilish secrets of thirteen generations have been buried and forgotten until now.