Wrocław in 1946 is the world after the apocalypse. Everyone seems to be tainted by evil. And yet, in Popielski's poor apartment, someone special appears. Professor Stefanus, a man who absolutely believes in human evolution towards good. He comes to Popielski with a job offer. The detective is to discover who, among the students of Stefanus's secret philosophy course, is the informer. Circumstantial evidence indicates that one of the three girls is a spy.

During the investigation, Popielski finds a trail of a strange Russian - Boroszwili, who hangs around Murawski's house. Following him, he ends up at Szaberplatz, where Boroszwili is doing business with Colonel Bogdylov himself. Now everything is starting to come together. Edward notifies Chernikov, who launches an internal investigation into the case of Boroshvili and Bogdylov.