Alois, manager of a remote mountain inn, loses his maid when she can’t stand his oversized Saint Bernard, Bohouš. When a ravenous guest arrives, Alois makes a wager: if the guest can out-eat Bohouš in one sitting, they earn a free week’s stay; if not, they must serve as the inn’s maid for a week.

Konvalinka, a notorious betting man, has become the scourge of the establishment. He can turn anything into a bet. During one such bet, when he is not ashamed to take advantage of the manager to win, he is noticed by the owner's brother, Bohus, who is visiting a friend. After finding out who Konvalinka really is, he decides to shake the bettor down. Since he works as the manager of a small South Bohemian pub, he sets up a big operation to punish Konvalinka. He is seconded in this plan by his cougar father-in-law and Bohouš's St. Bernard son Pepa.