Based on David Freedman's play Mendel, Inc., a poor man on the east side of New York invents a dish-washing machine and suddenly becomes rich.
Mendel got money from his oldest daughter Lilian for the rent, but he used it for his invention. His daughter Mimi needs shoes and wants a new dress, while her brother needs a dentist. Having paid for his patent and still owing two months' rent, Mendel sells a half interest to his brother-in-law Bernard, who makes a deal with Strudel. Strudel has a dentist for Lilian, and Bernard has a doctor; but Lilian met a lawyer named Milton at school who turns out to be all three. Bernard is fired as agent for not paying Mendel's rent. Mendel gets more money for his invention from Bessie that she was going to use to pay for insurance. Mendel shows Bernard and Strudel how the dishwasher works. The marshal demands three months rent from Mendel; Lilian cannot help because she gave the $500 for the invention too. Bernard and Strudel say the machine broke the dishes. So Mendel's wife Zelda goes to work, and Mendel does the housework.
Gassenheim arrives to tell Mendel he is going to manufacture his dish-washing machine and takes Mendel in his car. Zelda and her children want to move to the west side into a house Bernard has picked out for them; but Mendel bought their tenement with sixty rooms. Zelda and her children leave Mendel, who gets an architect to redesign his building into a "palace on the east side." Mendel gives his tenants two months free rent. He visits the west side to ask the doorman about his family on the tenth floor. Mendel tells Klaus he has a man (Strudel) to do for him all the sports rich people play. When Zelda stops getting royalty checks, she comes to see Mendel. Bessie is his social secretary. Mendel welcomes his family and tells them the royalty checks are stopped because of an injunction. Gassenheim comes in to take possession. Milton says that Gassenheim and Bernard are suing; but it is invalid, because Bernard signed his share over to Strudel first and never paid Mendel's rent. In the final scene Zelda and the children are all telling Mendel to dress up.
This film captures some of the flavor of living in an east-side tenement. The Jewish ethnic culture has its own idioms and charm. Mendel desires little more than to relieve the pressure of paying rent for his neighbors, though the rest of his family is eager to join the upper class.