In response to an unprovoked nuclear attack from the planet Ebon, a group of soldiers—representing Unified Earth—is sent to fight the enemy on their alien world. Captured en route to Ebon, the soldiers undergo physical and psychological torture and interrogation at the hands of the Ebonites, who possess the ability to control the five senses. The prisoners become suspicious of each other when their captors claim they have received cooperation in obtaining military secrets, which is further complicated by each one's past and ethnic origins, along with the unexpected appearance of high-ranking Earth officers among the hostile aliens. The earthmen are subjected to various interactive images of relatives and friends, which have been implanted in their minds during questioning, allowing them to feel a false sense of security, or to instill deeply hidden emotional conflicts. In the end, it is revealed that all of this is but a military "game", organized by the Earth officers to test their troops' loyalty and valor under intense interrogation and psychological stress. The Earth-Ebon war itself is a fake, as the Ebonites' initial bombardment was unintentional. Unexpected accidents and deaths having occurred during the test, the Ebonites—who are, actually, a peaceful and honorable alien civilization—eventually ask for such an immoral and inhuman experimentation to end at once; but, nonetheless, fail to prevent one last man from being killed...one of the conspiring Earth officers thought to be an illusion created by the Ebonites to trick the captives into revealing more information.

Originally scheduled to air on November 25, 1963, the episode was delayed until December 2 due to television coverage of the November 22, 1963 assassination and later funeral of President John Kennedy.

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