Transported to medieval Germany, Jason and his friends Charlotte and Squid have to use their wits and the power of a magical bugle to help the people of Coburg fight for freedom.It's going to be 12-year-old Jason's worst summer ever - nothing to do and no one to hang out with. His family moved from Toronto to a rundown old house near Cobourg, Ontario, once the home of his great-uncle. His musician mother is travelling and his dad, a thriller writer, is usually welded to his computer. Jason explores the attic, hoping for treasure, but finds only a battered old bugle. A couple of kids do turn up, but hardly the ones he would have picked as friends - Charlotte, who is Jason's age, and her little brother Octavius, known as Squid. Their grandmother knows a lot about the bugle and its previous owner - Jason's great-uncle, a WWI soldier.She teaches Jason to play the old horn and, along a misty country road, its magical music transports the kids to medieval Germany - the old walled town of Coburg. At first, Jason only wants to go home, but he soon learns he has work to do.Is his bugle the Wunderhorn of local legend - and Jason himself the hero of the tale, the shepherd king who can restore order in the land?