A sudden attack by the Klingons on a vulnerable neutral sector - a location of great strategic importance - puts the Enterprise on red alert, as the threat of a catastrophic war between the Klingon Empire and the Federation looms. Kirk and Spock beam down to Organia, the planet whose security is at risk due to the Klingon threat, and find that the inhabitants, who appear to be humans who have reached the medieval period of sociological and technological development, are not at all concerned that their world is currently being overrun by Klingon troops. Kirk and Spock try to conceal their identities, but fail, leaving Kirk and Klingon Captain Kor at each others' throats - until the Organians reveal their true nature and intervene in the impending war.
