Operation Barbarossa.

Operation Barbarossa is a kids TV show, based on the novel The Mysterious Boy by Ivan Kušan. It is a story about a boy who for some time lives in the belief that he is to blame for the death of a friend, a peer, who drowned in the Sava river. In order to cover up his death, the boy takes his name (because he had just come to Zagreb when he disappeared) also goes to another school. Thus, in two shifts (before noon - afternoon), he tries to be a student in two schools and gets into many dramatic situations. The riddle is, of course, solved by Kušan's main character Koko.