Mr.Wilson travels home aboard an airline with his wife. At first sight Mr.Wilson seems to be nervous of flying, by the way he is acting he seems frightened at the idea of being 20,000 feet in the air. However as our story moves forward we learn that Mr.Bob Wilson has in fact recently been discharged from a sanitarium, where he spent the previous 6 months recovering from a nervous breakdown which occurred, you guessed it, aboard a plane. While in the air Mr.Wilson's wife takes note of him not being able to sleep. "I'm fine, you go to sleep." He assures her that everything is alright and begins going over the past 6 months, saying that it's "astonishing" he can look back and put it behind him now.
Later on, the plane rumbles with turbulence because of a rain storm. Mr.Wilson looks out his window and is horrified when he sees a creature lurking on the wing. Mr.Wilson tries to convince himself that nothing is there but his curiosity gets the best of him as each time he opens his window curtain his eyes don't seem to trick him. The creature is there every time and he begins to believe a little more that he is not seeing things...or is he? Mr.Wilson tries his best to explain what he is seeing to the people around him but no one believes him. Every time he sees the creature and tries to get someone to look out the window the creature somehow jumps out of view. The rest of the episode is a psychological struggle for Mr.Wilson and the viewer. Eventually this creature begins tampering with the plain engine and our star has to take matters into his own hands in his own assurance that he is not slowly plunging into insanity but, in fact, experiencing something of the paranormal.
I enjoyed this episode because it really does a good job of spooking and disturbing the audience as the story progresses. It is very difficult to determine until the very end if Mr.Bob Wilson is right or not. It leaves you guessing until the final scene. This is indeed The Twilight Zone's best and most recognized episode. I just saw it yesterday and I can assure you it has definitely stood the test of time. The more I think of it the scarier it gets. I truly believe that the monster on the wing story (Nightmare at 20,000 feet) deserves it's praise as one of the most popular and best episodes on any show in all of television history.