In order for his teenage daughter Nelly not to flunk class for a third time, her father Eduard, a pastry chef, baits scholars with cakes to give Nelly private instructions in math and latin. Eduard is furious when a chimney sweep, Heinz, moves nearby, fearing that the soot will make his pastry dirty. Since Eduard only knows Heinz when he is dirty, a clean Heinz in a suit pretends he is a scholar to give Nelly private instructions, because he is in love with her. Due to a misunderstanding, Eduard thinks that Nelly's school teacher Klaus wants to marry her. When Klaus explains he has no such intention, Eduard quickly sums up Heinz at the engagement dinner, and thus Nelly is engaged.
One of Hans Moser's most famous films, "Black on White" is a light comedy where the comedian doesn't quite manage to rise to the occasion: he is rather acting happily more than actually being funny. The main problem is that the screenplay wasn't that well written nor rich with jokes, and thus Moser carries the entire film by trying to improvise jokes, giving it more effort than was his duty. There are some amusing situations here, such as when the main protagonist Eduard, a pastry chef, is furious that his neighbor is a chimney sweep, fearing the soot will besmirch his cakes. Eduard exaggerates by showing everyone a cake with a dark spot on it, and even goes to the manager, showing his daughter's dress in a foil with a dark patch, as evidence of the chimney sweep's dirt. In another, Eduard brags how the baited one private instructor with streuselschnitte and the other with a cake However, these are not enough to justify the movie, since everything feels thin. The love story between Nelly and the chimney sweep is neat and sweet, yet, just as it is the case with the jokes, these moments are today more convinceing with their charm than with their inspiration and skill.