The Camelot Code, Book 2: Geeks and the Holy Grail - Mari Mancusi

Sophie and Stu must get the Holy Grail into King Arthur's hands so he can drink from it and recover from a deadly illness. Simple, right? But Merlin's apprentice, Emrys, has accidentally turned the Grail into a gassy, fire-breathing baby dragon. And Merlin is the only one who can change it back. But Merlin's on holiday in modern-day Las Vegas. From sneaking a baby dragon through airport security to the ultimate showdown with the sorceress Morgana, deep in the land of Faerie, this new Camelot Code adventure will test not only the two geeks' courage, but also their very friendship.