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 action takes place during the Great Patriotic War in Belarus. The village in which the boy Kastus lived was located in the partisan zone. He soon made friends with the partisans, who became close people to him. The loss of his older friends was unexpected and difficult for Kastus...