A fortune-teller forecasts for Dr. Prelouc that he will marry the third poverty-stricken little girl he meets. Míla, the daughter of factory owner Janota, likes the doctor and with the aid of his housekeeper Amálka she insinuates herself into his household in the disguise of a poor seller of shoe-laces. She has prepared for her role beforehand by surveying the outskirts of the city where she met Vendelín Pleticha, who became her guide to the local pubs and teacher of the people's speech. Dr. Prelouc is inspired by the poor, uneducated girl and tries to teach her the rudiments of societal behavior, even literary language. Everything goes along until the moment he finds out that Míla is tricking him and that Pleticha is not the father she has passed him off to be.