The Howl of Avooblis — Charles Streams

Dagdron Obor and Earl Valorington have moved on from the Arches of Avooblis, and Earl has big plans to spend the summer preparing for their third and final year at the Adventurers' Academy. But then Dagdron's dad disappears, the sinister and powerful Backer attacks them, and Wendahl gives them a quest to rescue Dagdron's mom from Avooblis. Dagdron and Earl join with their academy companions, Elloriana Loftloomburg and Lita Valk, to search out Mazannanan's secret treasure all while trying to stay off the radar of Headmaster Gwauldron and uncover the identity of the Backer. Along the way they realize that a traitor may very well be among them and that they might not survive to become full-fledged adventurers after all.