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. When Felix’s friends almost mess up his date with Melanie, he shrinks them spontaneously to a tenth of their size. Just for a short time, he thinks to himself. But once Melanie has left, the magic ball to restoring his friends to their proper size has also disappeared. Is Melanie behind the thefts after all? In the process, Felix not only has to shrink himself, he also must confess his love to Melanie and admit his mistakes to his friends.
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 hated and long-since dead Director Hulda Stingbeard. A coincidence causes the former shrunken and skeletonized school principle to rise again. When she manages to return to real life she almost defeats Otto Leonhard, manages to shrink Dr. Schmitt-Gössenwein and Felix' parents, and takes over the school. It takes Felix, Ella and their gang to set the levers in motion to save the school and bring Dr. Schmitt-Gössenwein and his parents back to their original size again.
Impoverished former soprano Anneliese Behrens is forced to leave her house and collapses in an underground passage, when looking for a place to sleep. In the hospital, she learns that she suffers from a brain tumor and needs 24-hour attention. Although they have maintained no contact with each other, she will be hosted by her daughter, who, however, has already booked a Christmas vacation with her family in Thailand. The only solution is to take her mother with her.
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!
