Over the planet Excalbia, the Enterprise is intercepted by who appears to be Abraham Lincoln, floating through space. He extends an invitation to Kirk and Spock to visit the planet. Kirk, Spock and Lincoln are joined on the surface by an image of Surak, who initiated the doctrine of emotional restraint on Vulcan. A rock-creature appears and introduces Kirk and Spock to four more illusionary figures from history, from Earth's Genghis Khan to Kahless the Unforgettable. The creature pits the best and most noble - Kirk, Spock, Lincoln and Surak - against the most vile historical figures. The rewards for Kirk and Spock, should they survive, are their lives, and the lives of everyone aboard the Enterprise.
