O zázračné mouše.

A fairy tale that tells us that even an "idea" can be worth more than gold. Vašek wants to ask for the princess's hand in marriage. So he pretends to be Grandfather Know-All to get something extraordinary to give her as a gift. Grandfather gives him a non-existent magic fly. Kvido and Jáchym are also competing for the princess's hand. In the end, Vašek wins over both competitors with the help of his idea. However, thanks to the magic fly, he realizes that even a princess may not be true happiness, so he returns to the simple girl Vendulka.