A Delta Quadrant planet whose people built antimatter technology from the instructions carried by the Earth probe Friendship One, and suffered a catastrophe that left their world in nuclear winter.
Uxal is the planet visited in Friendship One. The probe of that name was launched from Earth in 2067 with greetings and technical knowledge for anyone who found it. When it reached this world, the inhabitants used its data to build antimatter reactors, and a containment failure poisoned the planet with radiation.
Starfleet asks Voyager to recover the probe. The away team finds the survivors living underground, sick and embittered, and their leader Verin takes hostages, demanding that Voyager move his people to another world. Lieutenant Joe Carey is killed during the stand-off.
With the help of the scientist Otrin, the crew devises a way to cleanse the atmosphere, detonating modified torpedoes that neutralise the radiation and clear the skies.