1947. Police captain Aleksandr Ratnikov investigates a series of murders in Leningrad. The trail leads to a technologist at a local fish farm, Pavel Vedernikov. It turns out that technologist Vedernikov is actually the former deputy head of the Nazi concentration camp for children "Grachi" named Gunther Zeiler. Skillfully posing as a Soviet citizen, Zeiler is hunting for his family's art collection, which disappeared during the war. The criminal is ready to walk over corpses, just to get what he wants and go abroad. Ratnikov intends to catch Zeiler at any cost: this Nazi is the only clue in the story of the captain's daughter, who disappeared during the war.