Two employees of a security service are found dead at a large construction site in Thuringia. Since the men were from Northern Hesse, the Kassel detectives Paul Lenz and Thilo Hain are asked for assistance. The victims had also been deployed to guard the construction site at the Kassel-Calden airport, which opened the previous year, and were apparently involved in criminal activities. Lenz and Hain try to prevent a catastrophe, but time is running out for them...