Riviere is on the ground waiting for the Patagonia mail, and as time passes he slowly realizes that the plane is lost. His reactions and thoughts are the main part of the story. He has to remain tough and devoted to his duty despite the loss, he must continue to send other pilots into the night to keep the mail moving. Riviere is also the one who must tell Fabien's wife that her husband is lost.
At a different level, the book is an attempt to analyze and explain duty and responsibility one can feel towards his work and his friends and the reasons why people like Riviere and Fabien would persist and continue in their work, despite the very real dangers.
When it was first publish the book was very well received and this was the book that made Saint-Exupery famous. Years later, in late thirties, after the rise of Facism, Saint-Ex was criticized for the ideas presented in "Night Flight". After all, many fascist atrocities were justified as "we were only doing our duty", "just following orders". I don't believe that such criticisms are justified. Saint-Ex always tried to look for the more noble emotions and motivations in man and the devotion shown by his characters was towards the improvement of the life of man.
As a writer, Saint-Ex was a perfectionist, revising his manuscripts on the way to the printer. But his obsession resulted in beautiful, poetic writing, and that shows even in translation. For example here are the first few paragraphs of "Night Flight":
Already, beneath him, through the golden evening, the shadowed hills had dug their furrows and the plains grew luminous with long-enduring light. For in these lands the ground gives off this golden glow persistently, just as, even when winter goes, the whiteness of the snow persists.Although "Night Flight" is fiction, the characters in it are based on real people. If you'd like to find out more about the people that Saint-Ex worked with as a pilot also read "Wind, Sand and Stars".
Fabien, the pilot bringing the Patagonia air-mail from the far south to Buenos Aires, could mark night coming on by certain signs that called to mind the waters of a harbor - a calm expanse beneath, faintly rippled by lazy clouds - and he seemed to be entering a vast anchorage, an immensity of blessedness.
Or else he might have fancied he was taking a quiet walk in the calm of evening, almost like a shepherd. The Patagonian shepherds move, unhurried, from one flock to another; and he, too, moved from one town to another, the shepherd of those little towns. Every two hours he met another one of them, drinking at its riverside or browsing on its plain.
Sometimes, after a hundred miles of steppes as desolate as the sea, he encountered a lonely farm-house that seemed to be sailing backwards from him in a great prairie sea, with its freight of human lives; and he saluted with his wings this passing ship.