The preeminent German engineer Habicht (Rudolf Hrusínský) works on a project to develop a rocket weapon. He cannot find a way to guide the rockets. Apart from that, he also has personal worries. His sixteen-year old son Bruno (Václav Sloup) has almost miraculous abilities in mathematics, but otherwise is simple-minded. He makes "swallows" of his father's plans for the secret weapon but at the same time tells his father about his gross errors in his calculations. Bruno's teacher dies in her house in a mysterious explosion. Habicht substitutes her with a young man (Vlastimil Hasek) who finds out that Bruno has a small launching pad in his room and extinguishes all those he does not like.