The protagonist of this story is Fritz, the oldest son of a mouse family. He lives with his parents and grandparents along with his 23 siblings. His father earns a living for the family by working at the local bakery with his best friend, Max. Max is a cat and a devoted vegetarian. To ensure that Max doesn't lose his job as a mouse catcher, he and Fritz's father put on a show every day, culminating in Max catching a mouse. However, just before Christmas, Fritz's father has to leave the town, and Fritz is supposed to take his place in his absence. This doesn't go without consequences. Fritz goes wild and forgets all the agreements. He goes beyond the limits, resulting in the baker taking stronger measures. In addition to some traps, four black cats also come into play. The situation becomes very dynamic, and only a battle plan can set the derailing train back on track. Thanks to the family's unity and the reliable friend Max, they manage to drive away the black cats. At least the baker's family separates from them. Naturally, a happy ending occurs, followed by a joint Christmas celebration in the bakery. The story is written continuously but divided into 24 chapters, making it suitable as an "Advent story" to read. Enjoy reading!