The Copernicus Legacy: the Forbidden Stone by Tony Abbott is the first in a series. This book is a fast paced adventure perfect for middle grade readers. Four friends travel to Germany for a funeral, but find themselves in a race to solve a mystery that could affect the entire world. The Forbidden Stone is packed with intrigue, puzzles and adventure.
The Boundless by Kenneth Oppel
The Paladin Prophecy by Mark Frost
The Iron Trial by Holly Black