Episode Title: "THE DEVIL IN THE DARK"
Production Number: 26
Original Air Date: 03-09-67
The U.S.S. Enterprise answers a distress call from Janus Six, a mineral-rich planet with a long-established pergium production station and colony. Several miners have been killed and machinery has been damaged by a powerful corrosive. A pump for the pergium reactor is stolen, and Captain Kirk orders Commander Giotto to lead the security troops into the mine to search for the creature responsible.
Commander Spock theorizes that the creature is a silicon-based life form that can emit a powerful corrosive to create tunnels through solid rock.
Captain Kirk locates the creature, and Spock uses the Vulcan technique of the joining of two minds, allowing him to share the creature's thoughts. They learn that the creature is called a Horta, whose race dies every 50,000 years with just one to care for the eggs to create the next generation. The Horta attacked the miners after they broke into the egg chamber and damaged many eggs.
They make an agreement for the miners to leave the Horta and its children alone, and the Horta will create tunnels to help the miners reach pergium and other valuable mineral deposits.
Factoid: The U.S.S. Enterprise has a supply of thermal concrete, used to build emergency shelters, which is composed mostly of silicon.
Dr. McCoy: "I'm a doctor, not a bricklayer."
Guest Characters: Commander Giotto, Lt. Leslie
Alien Races: *Janusan Horta
KEY: [brackets]=illusions *star=first appearance