Groundhog Day meets The Truman Show meets The Matrix is a description that may give some indication of this episode's mind-bending plot. What the story shares in common with all these examples is that it raises the question of what is reality. As such, it feels as if it might have come from the febrile imagination of Philip K. Dick (though it is in fact based on a short story by another master of science fiction, Frederik Pohl).
Many listeners will also be reminded of The Twilight Zone, as the story could very easily have been adapted for this series. In any case, this ranks as one of the very best X Minus One episodes of all. What is most striking at the beginning - when we first meet the protagonist and learn that he keeps reliving the same day, yet no one else seems aware that the day is repeating - is how modern its central idea feels; after all, Groundhog Day didn't bring a similar conceit to a wider audience until over thirty-five years later.
It's difficult to discuss any more about the plot without giving too much away, but one reason this is such a strong episode is that just when you think you have the story figured out, there is a twist that sends it veering off in a new, unexpected direction. Furthermore, with so many twists and turns in the plot, this means there are enough ideas here for two or three different stories.
Another reason this ranks so highly is that it is almost the archetypal X Minus One episode, in that it touches on a great many of the fears and concerns of the era that were explored throughout the series' run, including about the atomic bomb, consumerism, the advertising industry, electronic surveillance and secret conspiracies; it even manages to reference both Martians and Russians, the two major 'bad guys' of 1950s American science fiction.
Finally, the ending is bold and jaw-dropping, and packs a real punch.
X Minus One aired on NBC from April 1955 until January 1958. It was an extension of Dimension X which aired on NBC from 1950-51. The first fifteen scripts used for X Minus One were scripts used in the airing of Dimension X; however, it soon found its own little niche. The stories for the show came from two of the most popular science fiction magazines at the time; Astounding and Galaxy.
X Minus One: Tunnel Under the World by Frederik Pohl - 27:59