In this yuletide romance by the author of One Magical Christmas, Santa brightens a young woman's holiday season with a handsome rock star.   Student and Zumba instructor Izzy Grant leads a pretty normal life, but in the days leading up to Christmas an unusual encounter with a friendly Santa paves the way for the most wonderful and star-studded Christmas she's ever experienced.   Because at almost exactly the same time, Izzy also meets Seth Roberts--as in the Seth Roberts, bona fide rock star and lead singer of Scarlet Gryphon. As their connection grows, Izzy's Christmas countdown becomes a glittering whirlwind of after-show parties and classy restaurants--and does she have her mystery Santa to thank?