On stardate 41309.5, the USS Enterprise arrives at Persephone V to fetch Admiral Mark Jameson, a man of eighty-five, who is known for his legendary negotiation skills. Captain Picard relays a transmission to him from Karnas, the Governor of Mordan IV, who reports a dissident terrorist group has taken a Federation Ambassador and his staff hostage. The terrorists demand to speak with a negotiator and Karnas believes Jameson is the only man with the skills to handle the crisis.
Jameson, who is confined to a support chair, beams aboard with his wife Anne. As the ship proceeds to Mordan, Dr. Crusher calls Jameson for a regulation check up, but he refuses to be examined saying he has a terminal case of Iverson's Disease and there is nothing more she can do for him. Jameson then assembles a meeting with the senior officers to go over the details of the Mordan situation. He says the resistance wants Karnas overthrown, mainly because of the lack of productivity and deplorable living conditions that remain after a lengthy civil war.
Afterward, Jameson heads to his quarters where his wife takes notice that he appears stronger. Suddenly, he feels a sharp pain and doubles over, but he stops Anne from calling Dr. Crusher, assuring her that he had the pains before and they will pass. Later on the bridge, Picard offers Jameson to take the conn as they approach the Idini Cluster. Delighted by the offer, Jameson shocks everyone when he easily gets out of his chair and walks to the console. Jameson claims he has been undergoing a new therapy, but Dr. Crusher is skeptical. In private, she tells Picard that there is no recorded case of anyone recovering from Iverson's Disease, and there is no "therapy" she has ever heard of. Picard shares her suspicions and tells her to have a thorough look at the Admiral's medical records.
Later in his quarters, Jameson can almost fully walk again. He tells his wife the new treatment is working wonders. His wife even sees a change in his face as he looks 20 years younger. Suddenly, he is gripped by the intense pain again and falls to the floor. Anne calls for Dr. Crusher. In sickbay, Crusher detects an array of chemical stimulants in Jameson's tissue samples that seem to be rewriting his DNA, but none of the compounds can be identified. She also no longer detects any traces of Iverson's Disease. Picard can clearly see the Admiral is changing and confronts him. The Admiral explains he found a process that rejuvenates the body, a virtual "fountain of youth", offered to him by the natives of Cerberus II. He handled a treaty negotiation there several years ago and as repayment, the Cerberians gave him the secrets of reversing the aging process. He has been self-administering a combination of alien herbs and drugs for the past two years. Anne becomes upset, wondering why he has done this to himself. He explains he wanted to test it on himself first and that he had enough of it left for the both of them. He explains when the hostage negotiation came up, he wanted to make sure he was at peak performance and took an overdose of the serum.
When the pain subsides Jameson returns to duty and opens a secure line to Mordan to speak with Karnas. Careful that Karnas doesn't see his younger face, he asks him who specifically is behind the hostage taking. Karnas' attitude changes and Jameson senses the motives are personal. He realizes there are no dissidents and it is Karnas who has taken the hostages. Karnas confirms this, reminding Jameson of his treachery during his last mission which resulted in years of war. Jameson informs Picard that Karnas is behind the crisis and orders him to double their speed to Mordan, wishing to get there early as an element of surprise. Jameson, now appearing in his forties, debriefs the senior staff with his new rescue plan, pointing out that the capital city is still in ruins after the war and all that's left is a maze of "rat tunnels" with new structures built above them. He indicates a point where Karnas hid his hostages in the past, believing they are being held there now.
Picard asks for more insight on the Governor's demands, but Jameson isn't forthcoming. With three hours left until Mordan, Picard arrives at the forward lounge finding the Admiral sitting alone in the dark. Jameson fills in the background story behind Karnas' rise to power explaining that the Mordanite people were advanced, but still organized into warring tribes. Karnas' father, a chief of one of the tribes, was assassinated and Karnas retaliated by hijacking a Federation starliner with 63 passengers. He demanded the Federation supply him with weapons, but they refused. Jameson was later sent in and successfully negotiated the release of the hostages. However, it wasn't his golden oratory that saved them. He gave Karnas the weapons he wanted. Through Jameson's interpretation of the Prime Directive, he supplied an equal amount of weapons to Karnas' rivals, putting both sides on an equal footing. That decision caused 40 years of civil war. Jameson falsified his report to Starfleet saying millions of Mordanites died just to save 63 hostages. He now hopes he can vindicate himself.
The Enterprise enters orbit around Mordan IV, and Jameson assembles his rescue party. The group beams into the tunnels directly under the Governor's residence, but they are ambushed by a squad of Mordanite soldiers and a firefight ensues. Jameson charges ahead, but suddenly he crumples down and Data pulls him to safety. Picard orders an emergency beam out. Jameson is taken to sickbay but he wasn't injured by weapon fire. Dr. Crusher discovers his DNA is rejuvenating at such a rapid rate that his body cannot cope against the strain. From the planet, Karnas calls the ship, furious about the intrusion and demands to see Jameson now. Picard states the Admiral is ill, but Karnas doesn't care swearing a hostage will die every 15 minutes until Jameson beams down.
In sickbay, Jameson begs Picard to let him go saying its he who Karnas wants. Jameson beams directly to Karnas' office with Picard, Dr. Crusher, and his wife Anne. The Governor becomes outraged when he doesn't see Jameson but Picard says the young man is Jameson. Picard explains that before arriving here, Jameson took a de-aging drug to make himself stronger and this is what it has done to him. Karnas doesn't believe what he hears. Picard hands Karnas a data pad which contains the chronological images of Jameson's transformation, hoping it will provide proof. Picard says whatever he wanted from Jameson, he can no longer have, adding Jameson is only partly responsible for the war. He may have supplied the weapons, but Karnas made the decision to fight instead of negotiating for peace.
Jameson tries to speak telling details about their deal only Karnas would know, but Karnas isn't convinced. He says if it is Jameson, he would have a scar on his arm. Jameson rolls up his sleeve displaying the V-shaped blood scar on his wrist - the sign that secured the deal between them 45 years ago. Karnas is shocked and draws a phaser telling Jameson he will die by one of his own weapons. Karnas hesitates however, then finally lowers the weapon saying his revenge will be letting Jameson live like this. Jameson suddenly drops in agony and Anne moves to her husband's side. He says he remembers when Anne had golden hair and was so beautiful. He closes his eyes for the last time as she weeps. Karnas tells Picard the hostages will be released. Jameson is buried on Mordan, per Anne's request, and Karnas' approval. Returning to the ship, Picard talks with Commander Riker, mentioning, "The quest for youth, so futile. Age and wisdom have their graces, too." They leave orbit, and set a course for Isis III.