A lonely Border Guard officer, with a girl and a former villain, has to face a local corrupt Militia (Police) commandant and his people, in wild Bieszczady Mountains in the Polish East.
At the end of World War Two, Polish people move to the western lands vacated by Germans. But some ruthless profiteers pose as government representatives and intend to make off with loot from a deserted town they took over. One honest man stands up against them because he believes these goods belong to the people.
A young man, Kuba, is returning from the army. At home, an image of misery and despair remains: the father is seriously ill, and the mother has become emotionally attached to the man who exploits her and intends to take over the farm. After the death of his father, the young man guards the farm, but his girlfriend leaves him. Unable to bear the atmosphere of envy and resentment, Kuba leaves for the city.
Poland in 1946. A gang of 'Thunder' is committing violent robberies and murders and terrorizes the population of a large territory, consistently moving away from retribution. Captain Morava gets to knoa that 'Thunder' has a well-informed informant between his pursuers. The captain comes up with a cunning plan.