Watch Don't Make Grandpa Angry (1934) Official Trailer

Eman Vovísek drinks away his unrequited love for Liduška, who married his cousin, the factory owner Danek. Because Eman is aggressive when drunk, he is taken to a mental health facility, where he meets his uncle Hanibal. Hanibal has a breakdown after his wife Matylda broke up with him. Matylda wanted to be free so she could marry her first love, Uncle Jonathan, who is due to arrive from America. Jonathan sends a telegram saying he will stay in Paris. Such a situation does not suit Danek. He assumed that Liduška would be visiting from America and that he himself would go to his mistress in the meantime. He therefore visits Vovísek and persuades him to play the role of Jonathan.