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.