Among the Gruber family, the rumor spreads like wildfire that their wealthy American relative, Menyhért Gruber, is visiting Hungary with his daughter, Mary. Various plans are devised to exploit the rich relative. The boldest of them all is the plan of Bálint Koltay, who directly pursues Mary's hand. However, the young ones fall in love with each other so deeply that Bálint stands by Mary even when the "wealthy" Gruber informs him that he's bankrupt. At this point, the only thing left to arrange is for Bálint, who poses as a landowner, to actually present a noble castle to his future father-in-law.