Giessen's gymnasium director Gottlieb Taft hopes a ploy will make the school's centennial a prank-free success: he enrolls his nerdy nephew Ewalt Kunst as spy in Pepe's dreaded class. Some of Pepe's tricks are thus undone, others till succeed. The hated history teacher Knörz's new car and romantic war past as well as the upcoming Olympiad in Germany and the director's own soft spot for archeology provide fine occasions. Pepe's sister helps him, so he helps her make their dad Kurt accept her fiancé Heinz Thomas. Finally the ministry is tricked into sending not a bully teacher but a softy, Dr. Glücklich, who truly bonds with the rascals.