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 has Florentin Sneelin in its sights, 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. The teachers there enforced discipline and order using sometimes sadistic methods. Their wards did the same. There was a strict caste system among the children. Sneelin belonged to the lowest caste. He was a so called "Snow Child", one that his mother wanted "to foist" on his father.

A woman with a mysterious illness is forced into action when a group of terrorists attempt to hijack a transatlantic overnight flight. In order to protect her son she will have to reveal a dark secret, and unleash the inner monster she has fought to hide.