Charred bone remains and a skull are found in the embers of a summer solstice fire up on a mountain. A splintered hole can be seen in the top of the skull. The identity of the victim is soon determined: well-known veterinarian Dr. Fiala. As they investigate, Karin and Andreas come across suspicious growth hormones on Kreuzbrucker organic farms, of all places. First and foremost, they have to deal with livestock dealer and head of the district farmers association, Mr. Fluch, and his son, who had wanted to become a vet himself. The political influence of Fluch, a major farmer in the region, has serious consequences for the two young detectives.