In response to an urgent distress signal, the U.S.S. Enterprise ventures into the Ficus Sector to save the Bringloidis, a society whose planet is about to be destroyed by stellar flares. Upon assessing the situation, Riker beams aboard the entire Bringloidi civilization, which consists of about 200 humans and animals, led by a jovial man named Danilo Odell and his head-strong but beautiful daughter Brenna.
Picard soon learns that the Bringloidis had traveled from earth years ago with a second colony of humans. Not interested in remaining on Bringloid, the other group dropped off Danilo and his people and moved on to an unknown destination.
Suspecting that the second colony might also be in danger, Picard engages the crew on a search, which leads to the planet Mariposa. When an Away Team beams down, they learn that the entire Mariposan society is composed of clones made from the five crew members who survived their ship's crash landing.
Suffering from a degenerative condition known as Replicative Fading, the Mariposans ask the U.S.S. Enterprise officers to donate fresh DNA so they can clone strong new citizens. When Riker and Dr. Pulaski refuse their request, the Mariposans render them unconscious and take the valuable cells from their bodies.
Upon returning to the U.S.S. Enterprise, Dr. Pulaski is shocked to discover that both she and Riker are missing cells. The two beam back down to the Mariposans' lab to destroy their clones, which have not yet fully matured. The Mariposan leader is furious, since without new DNA, his race will soon be extinct.
In an attempt to resettle the Bringloidis and help the Mariposans, Picard suggests that the two races be left alone to breed naturally, rather than by cloning. Initially reluctant, both sides agree and the group that started out together on Earth ends up together again.