It was the end of a long, terrible nightmare when the girl Melanie Pölzl was able to escape from a dungeon five years after her kidnapping. The perpetrator then apparently saw no way out and threw himself in front of a train. The case was then officially closed. But when Moritz Eisner (Harald Krassnitzer) and his colleague Bibi Fellner (Adele Neuhauser) are called to demolish the horror house in Gieselbrunn in Lower Austria on a snowy winter day, the events take a dramatic turn. Because in the midst of the rubble, the former head of "Soko Melanie" Franziska Kohl was found dead in the same vaulted cellar - dying of thirst. The deeply shocked Moritz Eisner is convinced that it was not an accident.
And he soon realizes that he has to fight against an invisible network that extends to the very top of the police force and the judiciary. Eisner, who not only knew this colleague very well but was even in a relationship with her for some time, is almost entirely alone in his suspicion of a conspiracy. Only Bibi Fellner stands by him... "Abgrund" is an ORF production, made by Cult Movies and funded by the state of Lower Austria.