A man (Davos Hanich) is a prisoner in the aftermath of World War III in post-apocalyptic Paris, where survivors live underground in the "Palais de Chaillot" galleries. Scientists research time travel, hoping to send test subjects to different time periods "to call past and future to the rescue of the present". They have difficulty finding subjects who can mentally withstand the shock of time travel. The scientists eventually settle upon the protagonist; his key to the past is a vague but obsessive memory from his pre-war childhood of a woman (Hélène Châtelain) he had seen on the observation platform ("the jetty") at Orly Airport shortly before witnessing a startling incident there. He did not understand exactly what happened, but knew he had seen a man die.