||The Savage Curtain ||Green's stunt double
||Abraham Lincoln appears flaoting in space before the Enterprise (!). Understandably surprised, Kirk accepts the former president aboard the ship and gives him a guided tour. Lincoln invites Kirk and Spock to beam down to Exo III, a planet utterly hostile to Human life except for an unexplanable "oasis" spot on the surface. The invitation is accepted, and the officers beam down. They are met by an Excalbian, a silicon being who informs them that his people wish to investigate the Human concepts of good and evil to discover which is stronger. The good are to be represented by Kirk and Spock, Lincoln and Surak of Vulcan; their evil opponents are Ghengis Khan, Kahless the Unforgettable, Zora and Colonel Green. The aliens threaten to destroy the Enterprise in a matter of hours unless Kirk wins the battle.
The two groups skirmish on the surface, improvising weapons from whatever materials are to hand. Eventually Kirk and Spock manage to prevail, and the Excalbians release them and free the Enterprise to continue on its way.