Hubert Hrabe, known as Smart Boy (Karel Hermánek), is a Prague dandy who is always skirting the edge of the law. Like every likable rogue, he has a worthy adversary - Police Inspector Mourek (Petr Kostka), who has long been trying in vain to put him behind bars. However, this defender of justice, who is constantly trying to outsmart his "own" criminal, ends up becoming the victim of his own zeal while hunting forgers that are as good as any in Europe, as Hubert the Smart Boy, sets a trap for Mourek.