Jaclyn Moriarty 
Astonishing Chronicles of Oscar from Elsewhere [EPUB ebook] 

Oscar is just skipping school and hanging out at the local skatepark when he suddenly finds himself transported into a world very different to his. And this is his own account of his adventures from Monday to Friday last week. In the company of Bronte Mettlestone, Esther, Imogen and Alejandro, ordinary Oscar finds himself on a quest to locate nine separate pieces of a key, held by nine separate people, in order to unlock a complicated spell that had trapped the Elven city of Dun-sorey-lo-vay-lo-hey. If they dont succeed in their quest, on Friday at noon the spell becomes permanent, the Elves will be crushed to death and Oscar will be trapped in this magical world forever. (The account, it should be noted, has been written at the request of Oscars schools Deputy Head Teacher. She wants to know exactly what Oscar considered more important than coming to school last week.)