Planet (The Sons of Grekk)

An Earth-like planet was the homeworld of several intelligent creatures which resembled larger versions of spiders, butterflies, cockroaches and turtles (the latter of which were called Crustians). A man named Grekk left his sons there, where they lived in a castle, were served by Mechanislaves, and fought against the planet's other inhabitants (urged on by Deemon), keeping their captured enemies in the Pit.

The First Doctor arrived in the castle and stopped Deemon from killing one of Grekk's sons. When the sons of Grekk found him, they believed him to be a Crustian spy and took him to the Pit. The Doctor worked with the other prisoners to escape, trapping the sons of Grekk in the process. They then forced Deemon to shut down the hostile Mechanislaves and captured him. (PROSE: The Sons of Grekk)