The year is 1955. An agent in a balloon trespasses the West frontier, immediately afterwards shoots dead the driver of a lorry awaiting him in the woods, and takes to flight. The body buried under the stones and the gondola balloons is soon found. The finger prints at the bottle belong to the waiter Vorác who fled last year to Austria. The investigators Major Sojka and Captain Erba are tipping of the persons, detained last time at the frontier, a deaf-and-dumb man. The man puts down at the slip of paper his name Karel Neumann and also the statement that he suffers loss of memory. The doctors after thorough examination do not eliminate deafness and amnesia.