Planet (The Klepton Parasites)

A planet was inhabited by the Thains. It had an icy green ocean populated with fish.

In the 30th century, the Kleptons targeted the planet and built an underwater city, launching attacks on the Thain city with their bubble machines and giant creepers, intending to enslave the people.

The First Doctor, John and Gillian arrived and helped the Thains repel the invaders, followed the Kleptons to their city and freeing the slaves. The Doctor turned the creepers against the city's massive reactor, escaping with his grandchildren and the Thains just before the city exploded. (COMIC: The Klepton Parasites)