The enterprising Anton Klapproth runs a flying duck farm in the Eifel, but now he finally wants to experience a real adventure in the big city of Cologne. A visit to a sanatorium for the mentally ill seems particularly sensational to him, as there is certainly a lot going on there with the "Jecken" and would provide plenty of story material for his regulars' table. In return for a loan, Anton's nephew allows his uncle to stay at the Pension Schöller. However, the guests there are by no means men...