Secret construction plans by Aircraft Performance and Technologies (APAT), a Hamburg-based engine manufacturer and electronics developer, keep turning up abroad. Commissioner Cenk Batu is to track down the industrial spy as press officer Sinan Afra for the State Criminal Police Office. The head of development, Holger Lichtenhagen, is suspicious. When Sinan Afra is promoted to his personal advisor and Lichtenhagen asks him for a confidential interview, Batu hopes to finally find out more. But before it gets that far, Lichtenhagen's body is found in the port of Hamburg. At the funeral, Cenk Batu makes the acquaintance of Mia Andergast, Lichtenhagen's illegitimate daughter from an almost forgotten relationship, and soon gets caught between the fronts.