The boys will get a new class teacher who has discipline, they get in a lot of mischief, so much complaints that they have to read extra during the summer holidays to get started in class 4.
Three mice run, cavort, sing and dance around in the stores and restaurants a big city at night. They wind up in a café for an early-morning snack and stocking up on food provisions before they return to the safety of their den beneath a man-hole cover in the street.
Herr Werther, a new magistrate to the Grand Duchy of Walheim who is a violinist and poet, seems to have fate on his side as he meets and pursues a beautiful local woman, Charlotte.
The underage Rosemarie is still too young to run her inherited farm by herself; but she's more than aware that her foster father and the farm's administrator, the farmer Schlieker, is constantly skimming from the farm's finances to line his own pocket.