Pierce continues her successful blend of high fantasy, grisly suspense, and wry social commentary in this conclusion to the second series starring her quartet of adolescent mages. With control over earthquakes, lightning, volcanoes, and tides, the plump bespectacled pepperpot Tris may be one of the most powerful mages in the world; but the 14-year-old’s practical mind is more concerned about earning a living. A magical conference in exotic Tharios (which resembles a cross between the intellectual sophistication of Athens and the caste-ridden otherworldliness of India) seems a promising venue to learn some marketable magic. Instead, she bumps into Keth, a journeyman glassmaker, whose untrained powers over glass and lightning accidentally create a miniature living glass dragon, whom Tris delightedly adopts; less cheerfully, she takes on tutoring Keth in his dangerous magic, and he is equally reluctant to take lessons from a child years his junior. Meanwhile, Tharios is being stalked by a serial killer; and as the authorities worry more about avoiding ritual pollution than catching a murderer, Keth’s magic just might supply the key to stopping his rampage. There really isn’t much of a mystery here, since the eventual murderer turns out to be a total unknown, and the pace is too leisurely and repetitive to create much suspense. But Pierce (Lady Knight, 2002, etc.) more than makes up for these deficiencies with her appealing, well-rounded characters. Her fans will undoubtedly clamor for further updates on her likable young mages and their fascinating world. (Fiction. 11+)