Someone launches a group of antiquated chemical-fuel missiles at the Enterprise
, which easily destroys them. They set course back along the missiles’ path while Nurse Chapel calls Kirk down to Sickbay, forcing McCoy to give him the bad news: one crewman has a fatal disease and will die within a year. The crewman? McCoy.
He has one year to live.
Who is it?
The ship's chief medical officer.
McCoy determines to stay aboard the ship and carry out his duties as normal. Meanwhile, the Enterprise
tracks the missiles to their source: an asteroid on a collision course with an inhabited Federation planet. They soon determine that the “asteroid” is on a specific course and is hollow, with an oxygen atmosphere inside. Kirk takes Spock to investigate and McCoy insists on going as well. They beam down and find themselves on a seemingly normal planetary surface within the asteroid. Several men attack them, led by an attractive woman. McCoy is momentarily stunned by her appearance and knocked out, and Kirk and Spock are quickly captured. The woman, Natira takes them below where the residents dwell. They are brought into the Chamber of the Oracle, where Natira presents their weapons. Kirk says they come as friends but the Oracle speaks and gives them an electrical shock to indicate first what it feels like to be their enemies.
We come in friendship.
Then learn what it means to be our enemy before you learn what it means to be our friend.
The landing party is taken to private quarters where Kirk and Spock quickly recover, but McCoy takes longer. Kirk explains McCoy’s condition to Spock, and when the doctor wakes up he quickly realizes Spock knows. An old man comes in to provide a medicinal drink, noting that all of the people of Yonada have felt the Oracle’s wrath at one time or another. When Kirk mentions that they come from “outside,” the old man talks about how he climbed the forbidden mountains and “touched the sky.” He then screams in pain and falls down dead, a small ed spot glowing on the skin beneath his forehead. Natira comes in and dismisses his death as the results of old age, then greets them as friends. She is fascinated by McCoy and Kirk leaves the doctor with her while he and Spock go out to find the Chamber of the Oracle.
But things... are not... as they teach us. For the world is hollow, and l... have touched the sky.
Natira comes out and admits she has fallen in love with McCoy and wants to know if he will stay with her. Even after he explains he only has a year to live, she asserts she’d rather have only a year of complete happiness. Meanwhile, Kirk and Spock find the Oracle and notice that the writing on the walls is in Fabrina, the ancient language of a race who lived in the Fabrina star system before it went nova. They get into the chamber and make sure not to activate the platform that brings the Oracle computer on-line. They find a monolith with the Fabrina star system on it but before they can explore further Natira enters and asks the permission of the Oracle for McCoy to join with the People of Yonada. It agrees as long as he worships the creators and obeys their laws, but Kirk accidentally brushes the monolith and the Oracle shocks them unconscious.
But we're strangers to each other.
But is not that the nature of men and women, that the pleasure is in the learning of each other?
McCoy agrees to abide by the Oracle’s rules but asks that Natira let Kirk and Spock go. She agrees and they prepare to leave only to find that McCoy isn’t going with them. Kirk warns that if they can’t change Yonada’s course then they will have to destroy it but McCoy insists on staying. After they leave, McCoy accepts the Instrument of Obedience, a small implant that goes beneath the skin of the forehead, and he and Natira are married. She reveals the Book of the People to him where it is hidden in the monolith, and how it contains all of the instructions they need when they arrive at their destination.
Towards the end, the Fabrini people lived underground, as these people do, to protect themselves. Some of them must have been put aboard this ship and sent to another planet, and these are their descendants.
Kirk prepares to leave, having been informed by Starfleet to proceeded on his next assignment. However, they get a call from McCoy informing them about the book but the Instrument of Obedience kicks in and he collapses to the ground. Natira finds her husband like that and Kirk and Spock beam down and remove the Instrument. Kirk tries to explain that Yonada is a spaceship that has gone off-course, but Natira starts to feel the pain caused by her own Instrument and goes to the Oracle. It chides her for listening to heresy and Kirk, Spock, and McCoy arrive. The Oracle tries to kill her but they remove her Instrument as well. It superheats the room but Spock gets the Fabrini book and finds the controls to enter the control room hidden behind the Oracle. Kirk and Spock set Yonada back on its proper course, while Natira affirms that now that she knows the truth she will stay with her people.
You are forbidden to gaze at the book.
We mean no desecration to the faith of Yonada. We must consult the book.
It is blasphemy. You are forbidden. The punishment is death.
Among the Fabrini knowledge banks, Spock finds a number of medical treatments… including one for McCoy’s disease. They administer the cure and Kirk assures him that when the Yonadans arrive they will be there to greet them.
Dr. McCoy, the Fabrini descendants are scheduled to debark on their promised planet in approximately 390 days.
I think that we could manage to be in that vicinity at that time, if you wanted to thank the Fabrini personally.