In the late 40th century, Corey travelled with fellow SSS members Sara Kingdom and Mark Seven on the Space Exploration Team mission to the surface of the giant meteorite M5. Within two days, the Exploration Team, which included Sara's brother David Kingdom, had established a pre-fabricated base called Explorer Base One, protected by a force field.
They believed the meteorite to be devoid of intelligent life, but the base was attacked by Daleks while the SSS agents were searching the wider area. The only survivor from the crew was David, who was taken captive for interrogation. Discovering the Daleks' secret underground hideout, the SSS agents tried to rescue David and destroy the Daleks, but arrived too late to stop the Dalek ship escaping with their prisoner. (AUDIO: The Destroyers)