Franta Hronek is very dedicated to work and flying. The talented air-plane designer Ruda Kolar is also an excellent pilot, however he is not disciplined and is arrogant with his colleagues. He even starts flirting with the glass cutter Lída, even though he knows that she is Franta's girlfriend. By not servicing the windlass properly, Ruda causes an accident with Franta's glider. Lída, who is the only witness to the accident, doesn't reveal Ruda's guilt. The event shakes Ruda so much that he becomes aware of his faults and changes his attitude toward people and work.