One day Pavel, a young man wounded in the war, suddenly shows up at the home of a Moscow scientist name Krymov and claims to be his illegitimate son. Krymov denies this, but out of compassion he helps arrange a necessary operation for Pavel. Then certain things begin happening which suggest to Krymov that he may have a psychologically unstable fellow on his hands.
A drama set at the end of the Forties and the beginning of the Fifties. In a distant garrison town, life proceeds at a measured past. The officers drink and debauch, while the soldiers serve. Meanwhile accidentally unleashed human emotions are suffocated by the atmosphere of cruelty and hypocrisy.
A young teenage boy zealously tracks down criminals in this allegorical drama. Using the code name of Plumbum, Ruslan Chutko (Anton Androsov) delights in the pursuits of lawbreakers before informing the police, and he even turns in his own father when he catches him poaching fish. The questions are left to the viewer whether or not Plumbum is a crusading hero or a scoundrel. Western audiences may find the premise implausible, but children were known to inform on their own parents under the regime of Josef Stalin and others.