Karigan G'ladheon, now an experienced member of the Green Riders, the magical messenger corps of the King of Sacoridia, has succeeded in transporting the evil spirit of Mornhaven into the future, buying time for the protective D'Yer Wall to be repaired, but with everyone concentrating on keeping tainted magic from the Blackveil Forest out of Sacoridia, they failed to notice a threat much closer to home.

After obtaining an ancient book with only a few pages remaining, Lina and Doon return to Ember seeking the machine described in the book that might be able to aid their new community, Sparks, through the winter.