Original Air Date: December 23, 1977

The Enterprise arrives at the world of Neuterra just as a terrifying prophecy appears to be coming true. According to ancient legend, centuries earlier the planet’s leaders struck a bargain with a mysterious entity who promised peace and prosperity in exchange for the world itself at a later date.

Now that entity — appearing as a powerful, shape-shifting “Devil” — has returned to claim the planet.

While the population descends into fear and panic, Captain Kirk and the Enterprise crew must determine whether they are witnessing a genuine supernatural phenomenon or an elaborate deception.

As tensions rise among the planet’s leaders and citizens prepare to surrender their world, Kirk investigates the origin of the ancient bargain and uncovers clues suggesting that the terrifying visitor may not be what it appears to be.
In the end, the Enterprise exposes the so-called Devil as a technologically advanced con artist using illusions and psychological manipulation to exploit the planet’s ancient myth.

But the experience raises uncomfortable questions about whether Starfleet has the right to intervene in a civilization that had come to accept its fate — even if that fate was built on fear.