In The Dragon Charmer, [Fern] is 12 years older, but childlike in her reluctance to embrace her calling. So Fern's spirit is kidnapped by a tormentor and teacher, Morgus, a witch queen who lives somewhere beyond purgatory. Meanwhile, Fern's enemy from the first book is incubating a magnificent dragon for use as a weapon of world domination (the ultimate in scorched-Earth technology).
It has been said that the Harry Potter books have widened the market for fantasy fiction. If that is true, Fern's sequel will be of great interest, but I must caution that this is not children's fantasy. The Dragon Charmer includes a witch's admission of incest and her abuse of the hideous offspring. Also, [Siegel] deserves a dart for penning a gratuitous same-gender rape scene and then, incredibly, brushing off the horror as meaningless (the victim's body and spirit were in two different places, you see).