Neporažená armáda: A young farmer, Jan Aleš, is drafted from his native Pošumaví to join the army. Since he likes his new environment, he stays with the army as a long-term serviceman. He even successfully passes the exams for the military academy. There he becomes friends with his Slovak colleague Milan Jurčík. He studies diligently, but thanks to Milan he sometimes finds time to go out into the city. That is how he meets the factory owner's daughter, Zdenka, with whom he falls in love. However, her father is not very happy about the promising relationship.