The class is going to the lake. The students are supposed to swim and play pirates. Unfortunately, their plans are thwarted. The principal, her deputy, the hygienist and the children can't wait for the bus that is supposed to take them to their destination. And that's not the end of the unpleasant surprises.

Czesio falls into a black hole with a dragon at the bottom. His friends are terrified. However, the huge reptile has the mentality of a bear, preferring hard coal to human flesh. It turns out that he has already eaten the entire mine supply and is suffering from hunger. Czesio is even more surprised when he discovers pieces of real gold in a dark corner and learns that it is the "work" of the beast. In order for it to continue to excrete these treasures, he has to eat something. Unfortunately, the man working in the school boiler room defends the last handful of coal with his own body. Czesio and his friends have to do something that he will not like.