The year 1970 is politically marked by the détente policy initiated by Chancellor Willy Brandt towards the GDR. Meanwhile, Chief Inspector Otto Kappe in West Berlin is tasked by his superior to reopen an unsolved case from the previous year: In September 1969, the body of a young woman was found near the Blockhütte Nikolskoe in the Wannsee district. Forensic examinations revealed that the woman had been bludgeoned to death, but Kappe and his assistant Hans-Gert Galgenberg have been unable to clarify either the identity of the deceased or the circumstances of the crime. Kappe quickly realizes that the reopening of this case has a political background. The Office for the Protection of the Constitution suspects a connection between the murdered woman and the notorious smuggler Wilfried von Thalmann - which could lead to complications.