Jason and the Wonder Horn 1st edition

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, Germany, fight for freedom.

Bored to tears, Jason explores the attic of an old house his parents have moved him to in Cobourg, Ontario. He's looking for hidden treasure, anything. He finds only a battered old bugle. A couple of local kids turn up, but they're hardly the ones he would have picked as friends - a girl named Charlotte, who is Jason's age, and her little brother Octavious, who everyone calls 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. But there's more to that horn than he first suspects - along a misty country road, its magical music transports the three children to medieval Germany, to the old walled town of Coburg.

At first, Jason just wants to go home, but he soon learns he has work to do. Is his bugle the Vunderhorn of local Coburg legend? Is Jason himself the hero of the tale, the shepherd king who can restore order to the land?