While on a mission to observe the peaceful Baku race, Lt. Commander Data suddenly behaves as if having to fear for his existence. The immortal Baku, whose planet offers regenerative radiation and therefore incredible lifespans, live in harmony with nature and reject advanced technology. Their planet and their culture is secretly researched by the Federation associated with an alien race called the Sona. But the Sona intend to abduct the Baku in order to take the planet for themselves and for the Starfleet officials who all would like to regenerate their bodies. But they did not think of the loyalty of Captain Jean-Luc Picard and the crew of the Enterprise-E to the Prime Directive.