The Enterprise crew has been ordered to deliver Elaan, a princess from the planet, Elas to the planet Troyius where she will marry a member of the planet’s royal family. The marriage is hoped to bring peace to Elas and Troyius, which have been at war for many years. The planets border both the edge of The Federation and the edge of The Klingon Empire, which The Federation has been at war with for many years. The Federation hopes that by helping to facilitate this marriage that Elas and Troyius will be more likely to join or trade with the Federation, though why The Federation is particularly interested in these two planets is unclear until the end of the episode.
Elaan is vehemently against marrying a Troyian as she considers the Troyians weak and arrogant in comparison to the barbaric Elasians. However, Kirk is able to convince her throughout the episode that marrying a man that she has never met before and does not love is the “right” thing for her to do.
During the delivery mission, the Enterprise crew notices that they are being followed by a Klingon ship. Later, one Elaan’s bodyguards sabotages the Enterprise’s warp drive, making it impossible for the Enterprise to outrun the Klingons or attack them. The Enterprise must receive new dilithium crystals in order to repair the warp drive.
Spock notices an energy reading coming from Elaan’s necklace. The necklace was given to her from the Troyians as a wedding gift. Elaan claims that the jewels are common stones on Elas and Troyias and that they are of little monetary value. Kirk and Spock realize that the necklace is made of dilithium crystals and that they can use them to power the warp drive
Elaan: “It is of little value. They are common stones.
Spock: “THESE are common stones? See captain? Here and here.”
Kirk: “Common stones? Now I see why the Klingons are interested in this system.”
Kirk to Elaan: “May I have this?”
Elaan: “If I can be of any help, of course.”
Kirk: “You may have just saved our lives.”
The prevalence of dilithium on these planets also explains the interest of both the Federation and the Klingon Empire in the two planets.
Following the Enterprise’s escape from the Klingons, Elaan is safely delivered to Troyias. As a result, The Federation has gained the trust of the two planets and can negotiate trade agreements with them for their dilithium.
Once again, Star Trek like many other negative energy narratives equates life with energy. The Klingons are willing to murder the Enterprise crew to prevent them from trading with the Elasians and the Troyians. The Federation is also willing to assist in selling a woman into slavery, or as they put it, marriage, for the sake of obtaining dilithium.