A hiker is found dead in a remote forest that is popularly known as the "Murder Hole." Opposite the victim is a melting snowman with one eye missing. The start of a series of murders in the forest area near Freudenstadt. The handwriting is always the same: all victims show frostbite, while the left eye is covered with a black gem. The investigative team Maris Bächle and Konrad Diener target Florentin Sneelin, a reproductive doctor who lives in a romantic moated castle whose ice cellar not only stores champagne. The suspect knew the victims from a stay in a children's home many years ago.

During the investigation, the inspectors discovered that the teachers in the children's rest home, where Florentin Sneelin was also staying, enforced discipline and order using sometimes sadistic methods. Their wards did the same. There was a strict caste system among the children. Torment and torture were the order of the day between the young inmates of the home. Sneelin belonged to the lowest caste. He was a “snow child,” one that his mother wanted to “foist” on his father. While the main suspect is in custody, more dead people are found. The handwriting of the murders committed also remains the same. The Freudenstadt dual leadership must now assume that there are several perpetrators and a common motive. In addition, the unpleasant ex-colleague Martin Coerde shows up in the Black Forest town and energetically asks questions. When Maris Bächle also comes into the perpetrators' sights, a race against time begins.