Brother and sister dragonology students Daniel and Beatrice Cook are looking forward to returning to their studies with Dr. Ernest Drake and Erasmus, their half- dragon tutor. But what they learn is that the evil dragonologist Alexandra Gorynitchka, who is bent on controlling (or destroying!) all the world's dragons, is searching for the fearsome Hammer of the Dragons-an ancient weapon that can kill hundreds of dragons in a single stroke. So it is up to Dr. Drake and the children to pursue her to the Lost Isle, where Alexandra is amassing a large army of enslaved dragons. There the siblings learn of the Dragon Prophecy, which says that the return of the Hammer of the Dragons can only be stopped by two children "wise beyond their years in the ways of dragons." Could Daniel and Beatrice be the children in the prophecy?