Laura Anne Gilman 
Grail Quest #1: The Camelot Spell [EPUB ebook] 

On the eve of the Quest for the Holy Grail, every adult in King Arthur’s castle falls into an enchanted sleep. The future of Camelot rests on the shoulders of fourteen-year-old squire Gerard, who has dreamed of becoming a Knight of the Round Table his whole life. With the help of Newt, the stable boy, and Ailis, a young maidservant, he must face terrible dangers, including a monstrous bridge troll, a wise and scheming dragon — and finally, a dark, powerful force that will stop at nothing to destroy King Arthur, the knights, and the entire realm of Camelot.