Customs officer Robert Riebsahl is murdered. The customs station is shaken. Riebsahl was considered a particularly correct civil servant. Klara Blum and Kai Perlmann are looking for a motive for the crime. Apparently Riebsahl was on the trail of irregularities in the customs station. In view of the brisk smuggling activities at the border, it is obvious that one or the other colleague is involved in shady dealings. For example, the young customs officers Marie Schreiber and Kevin Kümmerle, whom Riebsahl secretly photographed at work shortly before his death. The two commissioners encounter a web of corruption and favoritism. But is this actually the motive for the murder, or are they dealing with an entirely different drama?