Gorn offensive at Parnassus Beta

The Gorn Hegemony, a predatory reptilian power known to Starfleet only through scattered and terrifying encounters, began massing along the Federation border. When the Gorn struck the colony of Parnassus Beta, the USS Cayuga, under Captain Marie Batel, was destroyed in orbit, and a Gorn interference field cut off communications and transporters.

Against orders limiting the Enterprise to gathering intelligence, Captain Pike sent a landing party to the surface, where it found colonists in hiding and engineer Montgomery Scott, a survivor of another lost ship. Spock and Christine Chapel, stranded aboard the Cayuga's wreck, steered its saucer into the Gorn tower to bring down the field. But many of the landing party and colonists were seized by the Gorn, and Batel had been implanted with Gorn eggs.

Pike defied a withdrawal order to pursue a Gorn fleet. His officers freed themselves aboard a Gorn ship and the captives were beamed to safety, while the Enterprise bluffed and blinded the Gorn armada into retreating. Batel was saved by a treatment using Una Chin-Riley's Illyrian blood. The attack made it clear that the Gorn now posed a direct threat to the Federation.