Downer (The Spellkey) fashions a witty fantasy from several plot lines that come together into a satisfying denouement. Wycca, a pregnant wyvern belonging to a wizard named Gideon, falls through a "bolt-hole" ("a kind of magical rabbit-hole through Time") that transports her from ancient England to a spot near the home of young Theodora in modern-day Massachusetts. Gideon fears that his nemesis, Kobold, will track down Wycca and turn the dragon against Gideon; he must track the wyvern before Kobold gets to her. (The description of his emergence in the 21st-century Club Golgotha is a hoot: "To a wizard from the thirteenth centry, there was little to distinguish the club's dark, cavernous interior and its ghoulish inhabitants from the court of a demon king"). Meanwhile, Theodora, a collector of modern-day "Wizards & Wyverns" cards, finds a card missing from Gideon's magic deck and thinks it's the one she needs to complete her set. The race is on to see who will win at this complex game of lost and found. Downer takes a staple of fantasy—a dragon—adds a dash of humor and fashions Wycca as "a cross between the swiftest falcon and the most tireless hunting dog"; she lays an egg in a tower overlooking Boston Harbor and becomes addicted to chocolate after squeezing through a candy factory vent. The rest of Downer's crew are just as much fun, including Merlin, the helpful Harvard professor who comes to Gideon's aid, and Mikko, Theodora's mysterious nanny. Readers will likely hope that the seeds planted at the novel's conclusion suggests a sequel (having to do with Theodora's heritage). Ages 10-14. (May)