In the basement of Instytut Badań Czwartorzędu, a little land called Szuflandia is located. It is inhabited by dwarves living in poverty under the dictatorship of Kilkujadek (the Big Eater) who guards access to the world of people - the title's King Size. It is only a mysterious elixir that can make the dwarves achieve human height. One day, one of them, the alchemist Adaś, discovers the composition of the mixture.