It is the year 2000. The parents of twelve-year-old Péta are worried about the boy. He has made a flying machine on the model of a bird, but it crashed when he tested it and he broke his arm. His father Mísa goes back in his memories to the year 1975, when he was the same age as Péta and also experimented with various inventions. He tells Péta about a stone radiating a blue light which affected the workings of engines and the growth of flowers. One day the stone disappears. Mísa finds it on the bottom of an aquarium by which his five-year-old sister Káta sits drawing. The little girl claims that the stone has come from the stars.