The body of Stella's physics teacher Torben Fendrig is found in the Köpenick prison, which has been empty for years. He had been locked in a cell and died of thirst there. Fendrig had only recently inherited millions. Are Robert and Mavi dealing with a ransom demand that got out of hand? When they find out that Fendrig wanted a divorce, his wife Marina comes under suspicion. At the same time, Robert and Mavi take a closer look at Fendrig's students. The formerly popular teacher had suddenly become a schoolyard terror. And Fendrig had his sights set on one of Stella's classmates in particular: Jörn Hankwitz. Jörn is part of the "roofer scene" and climbs illegally onto office roofs and factory buildings at night for an adrenaline rush. The higher and more dangerous, the better.