Adeki was a planet.
While fishing there, the Seventh Doctor met what he thought were some of his prior companions: Adric, Sara Kingdom, Katarina, Jamie McCrimmon and Peri. Also, some of his previous incarnations appeared. They all turned out to be savage shape-shifting Gwanzulum, who had killed all the planet's inhabitants. They were stranded and hoped to trick the Doctor into helping them leave. The Doctor realised this and escaped without taking any of them with him. (COMIC: Planet of the Dead)