Eleven-year-old outsider Stephan arrives at Castle Schreckenstein, an all-boys boarding school, where he learns about life within a community and soon finds himself being part of a funny 'pranks-competition' the boys are currently fighting against the neighboring girls of Castle Rosenfels. When the girls have no choice but to move to Schreckenstein after a failed prank, life at school is suddenly nothing like it used to be...

Felix's school is haunted again, only this time it's not the benevolent spirit of school founder Otto Leonhard and the nuisance he caused, but the once hated and long-since dead Director Hulda Stingbeard. A coincidence causes the former shrunken and skeletonized school principle to rise again, leading to chaos...

Already having a hard time adjusting at his new school, things take a turn for the bizarre for eleven year old Felix when he accidentally shrinks his strict principal to only fifteen centimetres in height!

Melanie is a new pupil at the Otto Leonhard High School, and Felix takes a real shine to this newbie, much to the annoyance of Ella and Felix’s gang. They believe that Melanie is responsible for a number of small thefts that have been happening at the school since she arrived. Events take a drastic turn when the class goes on a school trip...