Felix, a 12-year-old boy from outer space, during the summer holidays gets admitted into a summer children's sports camp. Few people know in the camp that Felix is not there by chance, and a few days ago he was created in a school laboratory because a space intellect sent him as an agent to planet earth to study humans. He is assisted by an ordinary boy Boris and a teacher who explains Felix local traditions and customs.

The telefilm follows the fun adventures of two average students, Vovka and Valerka, who, while searching for an underground river, realize that their efforts won't succeed without knowledge.