Summer at Lake Constance. The Bregenz Festival is just about to open, resulting in a noticeable increase in the number of suits, costumes, and hats along the shores of the Upper Lake. A surprisingly fierce storm rushes in from the south on the evening before the premiere, abruptly disrupting the gentle atmosphere and uprooting numerous trees along the shoreline. The day after the storm, the body of a man is discovered in Lindenhof Park. Soon, Schielin and his colleagues learn that he was not a victim of one of the uprooted linden trees, but had been poisoned.