Adults have labelled everything in this world into good and bad, useful and unnecessary. Flies, for example, are an extremely boring and unpleasant phenomena, better to be killed off. Little Lilly has decided to stand up for the flies. She even presents a scientific tractata, arguing pro and contra. In protest against her father’s activities Lilly starts a hunger strike. In result the little girl becomes even less, falls into the vacuum cleaner, from there to dump and rather perilous situations. But then, it is the flies who come among others to save the girl and a happy ending of the film.