Student Šimon comes to the agricultural cooperative in the typical South Bohemian village of Hoštice for a holiday internship. He gradually gets to know the peculiar inhabitants of the village and tries to experimentally test his theory that milk production depends on the culture of the environment in the local cowshed. The management of the cooperative doesn't even want to hear about the experiment, but everything changes when word spreads around the village that Šimon is the son of the chairman of the regional agricultural administration. He is also called Plánička. The student will be accommodated by the Škopkov family, while their daughter Blažena will be tasked with finding out how it really is. However, everything is complicated by the horrible jealousy of Blažena's suitor Venco...