A young couple escapes from a mobile home in a forest not far from Regensburg. The couple is being pursued by the RV driver and his accomplices. The young man is caught, the woman is able to escape her pursuers, Alexander "Gypsy" Scherer and the Bulgarian Bojko Jankov. The next morning the young man is found dead with his stomach cut open. The dead man is Hassan Sabuni, a Syrian refugee who, in the current crisis, sold himself to a drug cartel smugglers: as a "body packer" he was supposed to transport swallowed heroin to Germany. Inspector Ellen Lucas, Tom, Boris and Nina Friedrich, who has just joined the team, are affected by the meanness and brutality of the crime.
The police station was put on high alert when it became clear that Leila Sabuni, the dead man's sister, had to get rid of her heroin balls within 24 hours, otherwise there was a risk of fatal poisoning. Lucas and her team determine that Regensburg is the end point of the so-called Danube route, which is operated by international Bulgarian drug smugglers. The operational head is Bojko Jankov, who bribes customs officers and police officers along the route. Also the German police? Criminal counselor Harald Leinenweber is brought in as reinforcements from Munich. Should he control Lucas, or is the political explosiveness of the case too big? Lucas focuses on finding Leila, and her investigation leads her to a refugee home to live with the fugitive's sister, Qumar Sabuni.
The case spirals out of control when Boris begins investigating on his own and it turns out he's involved in drug smuggling. The situation escalates when Boris is kidnapped. When the money is handed over, there is a deadly exchange of gunfire. As Commissioner Lucas understands why her colleague Boris had to act as she did, she also knows where the culprit can be found.