Captain Ronald Tracey was a Starfleet Captain in command of the Constitution class USS Exeter in the 2260s.
In 2268 the Exeter came to the planet Omega IV. Captain Tracey and a small landing party from the ship beamed down to the surface of Omega IV, where they encountered a village inhabited by a people known as the Kohms. The majority of the landing party beamed back up to the Exeter while Tracey remained on the planet surface to make arrangements with the natives for a planetary survey. Unfortunately, the people who beamed back to the Exeter took a virus with them, which swiftly reduced the crew of the Exeter to piles of dried-out trace chemicals from the Human body. The crew lived long enough to inform Tracey of what was happening to them, and to record a warning message for whoever came after them.
Alone on the surface of Omega IV, Tracey decided to violate the Prime Directive and intervene on the side of the Kohms in their war against the Yangs. Captain Tracey learned that people on Omega IV lived a very long time, and thought he had stumbled upon a fountain of youth.
Captain Kirk and a landing party from the Enterprise arrived to discover what had happened, and heeding the warning of the medical officer beamed down to the surface of Omega IV. Tracey informed Kirk that they were all infected and could not leave the planet.
Kirk and his party quickly determined the truth, and that Captain Tracey had been violating the Prime Directive. Outside the village Spock found the remains of several thousand Yangs who were all killed by Captain Tracey. They were unable to take him into custody as the local Kohms backed Tracey. Tracey murdered an injured security officer and had the remaining crew taken in to custody.
Kirk and Spock were able to escape from Kohm custody, and make their way back to where McCoy was working to cure them. Once there they learned that they had built up immunity to the Omega IV virus, and that they could leave any time. They also find that a long-ago nuclear war on that world had both reduced civilization to barbarism and left the survivors with extended life-spans. When Spock tries to communicate with the Enterprise using a jury rigged computer, Tracey comes in a vaporizes the computer, injuring Spock in the process. Kirk and McCoy confront Tracey about his actions, and tell him there is no magic fountain of youth on Omega IV, that people live for a long time there because it's natural for them to do so. Realizing that his actions have been for nothing, Tracey loses whatever grip he had left on his sanity as he marches Kirk outside. After a short fight, both men are captured by the Yangs.
Tracey, Kirk, and the Enterprise party are hauled off to the Yang headquarters. There Kirk realizes that the Yangs are in fact that world's equivalent of Yankees who are fighting to reclaim their homes from the counterpart Communists. Playing on Yang superstitions, Tracey manages to force Captain Kirk to face him in a duel. While the men are fighting, Spock uses a telepathic suggestion to get an Omegan woman to open a communicator, signaling the Enterprise. Kirk soon gains the upper hand and puts a stop to the fight with a blade at Tracey's throat. Kirk refuses to finish Tracey despite the urging of Yang leader Cloud William that he do so.
At that moment Lieutenant Sulu and a security team from the Enterprise beamed down. They placed Captain Tracey under arrest. The once respected Starfleet Captain was returned to Earth in disgrace.