Eleven-year old Mísa has the temperament of a proper boy and endless problems with the grown-ups. It is no wonder that he longs to become an adult without further delay. Mísa keeps house together with his father and has various duties. After a failed attempt at dish-washing he goes off to the research institute where his father is working on an important invention. He is trying to produce a substance that would make poultry and other animals bigger and thus help the struggle against famine in the world, but so far he has only managed to produce a shrinking substance. After his father leaves the laboratory, Mísa mixes up different ingredients and makes the growth substance. He drinks it and instantly becomes an adult. His father, conversely, turns into a toddler after drinking the shrinking substance with his beer by mistake.

Black comedy about a genius inventor and two young, smart and beautiful women. Both of them putting all their effort into getting the one man. This will inevitable lead to all sorts of mischief, crime and even a murder. This murder-comedy, shot at the dawn of normalization has intentionally broke off from any connection to the reality of its time. The director Zdeněk Podskalský has focused on creating intriguing story lines, revolving around the two endeavouring female characters who are fighting for the same man. Two competing parties are not only ready to kill the other, but also (if necessary) the potential groom. This film has enabled the members of the cast, composed mainly of the brightest stars of the Czech acting scene of that time, to show an incredible acting range, from the lightest comedy to the darkest cynical morbidity.