Max can hardly believe his luck: In a retirement home, he has finally found a gang that will let him join! Admittedly, it's the oldest and most wrinkly gang in the world - but that doesn't matter. He's found the best friends a 10-year-old could wish for in the elderly Vera, Horst and Kilian. Especially when, like Max, you're bullied in your new class and need help. But the gang's attempt to improve his school situation backfires. Horst, a former Bundesliga soccer coach, challenges Max's over-ambitious gym teacher Stöhle to a soccer duel: the school team including Laura and Ole against a selection of old geezers plus Max! And then the castle is haunted and a new case begins...

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.

It’s Valentine’s Day at Finja‘s school, and this year, the fifteen-year old is responsible for delivering roses and letters to the other students. Everything goes to plan until, at the last minute, her little brother Malte hands her one final letter – to a male classmate.