The
Federation starship Enterprise has been directed to make contact with a reclusive species known as the Melkotians. As they approach the Melkotians' planet, they encounter a probe carrying a warning for them to stay away. Crewmembers hear the warning in their native languages, suggesting that the Melkotians are
telepaths. Despite First Officer
Spock's warnings about the formidableness of telepaths, Captain
Kirk orders the ship to remain on course. Once in orbit, Kirk, Spock, Chief Engineer
Scott, Chief Medical Officer Dr.
McCoy, and Navigator Ensign
Chekov transport to the surface. They are met by a Melkotian emissary, who declares that they have been condemned to death for trespassing. The landing party then find themselves in an abstract landscape that resembles an
Old Western town, though many buildings are only simple wooden facades. Furthermore, they find their
phasers have been changed into
six-shooters, and they cannot contact the
Enterprise. Exploring the town, they find a newspaper dated October 26, 1881, the date of the infamous
gunfight at the O.K. Corral. The townspeople believe the landing party are members of the
Cowboys: Kirk as
Ike Clanton, Scott as
Billy Clanton, McCoy as
Tom McLaury, Spock as
Frank McLaury, and Chekov as
Billy Claiborne. The crew soon discovers that men dressed as the
Earp brothers;
Virgil,
Wyatt, and
Morgan, as well as their deputy
Doc Holliday, are preparing to fight them at the appointed time. Knowing that in real history the gunfight was fatal to most of the Cowboys, the
Enterprise crew try to change their fates by getting the sheriff and the townspeople to stop the fight and even attempt to negotiate with the Earps, but nothing works. However, when a barmaid, Sylvia, gets close to Chekov, a jealous Morgan Earp shoots him dead. Spock remarks that the real Billy Claiborne had survived, suggesting that the day's events could be changed in other ways. To that end, Spock creates an improvised tranquilizer
gas grenade to subdue the Earps before the shootout and is surprised when the gas fails to work. The time of the shootout draws near; a defiant Kirk and the landing party suddenly find themselves at the O.K. Corral, with the Earps approaching. Spock realizes from the failure of the gas grenade and the "death" of Chekov that the world they are in does not conform to the laws of reality and persuades the others that as long as they are convinced of that they cannot be harmed. Kirk has Spock
mind-meld with the rest of the team to imbue them with absolute conviction. Thus, when the Earps and Holliday open fire, their bullets pass harmlessly through. Kirk beats Wyatt Earp in a fistfight and disarms him, but throws his own weapon away rather than avenge Chekov's death. The crew then find themselves on the
Enterprise bridge, including Chekov, who survived perhaps because his mind was only on Sylvia. The Melkotians make contact, inquire about Kirk's refusal to kill, and finally welcome the
Enterprise to approach their planet. == Production==