In the summer of 1952, the divide between the two German states hardens. West Berliners are no longer allowed to enter the GDR without permission, and under Walter Ulbricht, the SED decides on the systematic establishment of socialism. When Hermann Kappe begins investigating the case of the murdered merchant Wolf-Dieter Grassnik, he is unaware of the connection to the spectacular robbery at the railway ticket office Unter den Linden. Did someone want to take Grassnik's share of the loot? When the victim's partner, Hildegund Hribal, also disappears without a trace, Hermann Kappe is at a loss. As a witness, she could clarify Grassnik's involvement in the robbery. Then Kappe receives a tip that Hildegund Hribal is at the broadcasting house on Masurenallee. However, British soldiers block access to the broadcasting house.