Lieutenant Commander Data (Brent Spiner) is temporarily transferred to an undercover mission observing the peaceful Ba’ku people. While on their planet, he malfunctions and reveals the presence of the joint Federation–Son’a task force observing the Ba’ku. Admiral Matthew Dougherty (Anthony Zerbe) contacts the USS Enterprise-E to obtain Data’s schematics but adamantly states the presence of the Enterprise is not needed. Captain Picard decides to ignore these orders and takes the Enterprise to capture Data. After stopping Data, Captain Jean-Luc Picard (Patrick Stewart) becomes suspicious of Dougherty’s insistence that the Enterprise is no longer needed. His crew investigates the cause of Data’s malfunction. They discover that the Ba’ku are technologically advanced, but have rejected the use of advanced technology in their daily lives. Due to unique radiation or “metaphasic particles” emanating from their planet’s rings, they are effectively immortal. Dougherty’s allies, the Son’a, are a decrepit race who use medical techniques to prevent death; their excessive use of cosmetic surgery gives them a mummified appearance. The Enterprise crew also begin to experience the rejuvenation effects of the planet: Lt. Cmdr Geordi La Forge (LeVar Burton) finds his eyes have regenerated and he no longer requires ocular implants; Commander William Riker (Jonathan Frakes) and Counselor Deanna Troi (Marina Sirtis) rekindle their long-abandoned relationship; and Picard develops a romantic relationship with the Ba’ku woman Anij (Donna Murphy).
Picard and his team discover a cloaked Federation ship containing a gigantic holodeck, set up to recreate the Ba’ku village. Data’s malfunction stems from a Son’a attack, received when he discovered the cloaked vessel. Confronting Dougherty with his discovery, Picard learns that Federation officers and the Son’a plan to move the Ba’ku to the ship so that they can collect the source of the planet’s radiation, destroying the planet in the process. Dougherty orders Enterprise to leave. Picard convinces his crew that the rejuvenation benefits of the radiation do not justify Dougherty’s plans for the Ba’ku or the destruction of their planet. He arranges to alert the Federation while the Ba’ku are evacuated.
Mineral deposits on the planet cause a transporter malfunction, stranding the Enterprise crew on the planet. The Son’a send robotic probes to locate and capture the fleeing Ba’ku. Their leader, Ahdar Ru’afo (F. Murray Abraham), convinces Dougherty to allow two Son’a ships to attack the Enterprise. Riker prevents the ships from attacking and the Enterprise escapes. Their plan exposed, Ru’afo insists upon harvesting the radiation source immediately. Picard reveals to Dougherty that the Son’a and the Ba’ku are part of the same race: the Son’a are a recent splinter faction of Ba’ku who gave up their bucolic existence a century earlier to embrace the use of technology. They attempted to seize power but failed, and the Ba’ku elders exiled them from the planet, denying them the rejuvenating effects of the rings. The Son’a turned to artificial means to extend their youth and lives. The Son’a kill Admiral Dougherty when he refuses to allow Ru’afo’s scheme to continue.
Picard, Anij, and several Ba’ku are transported onto the Son’a ship. After convincing the Son’a Gallatin (Gregg Henry) to help him, Picard masterminds a ruse to transport Ru’afo and the Son’a to the giant holoship. Ru’afo discovers the deception and transports to the radiation harvesting ship to start the process himself. Picard follows him and destroys the harvester and Ru’afo. The remaining Son’a are forgiven and welcomed back by the Ba’ku. Picard arranges a meeting between Gallatin and his Ba’ku mother. The Enterprise crew take a moment to enjoy their rejuvenated selves before returning to their previous mission.