In the conclusion of the eight-part story "The Invasion," the Doctor (Patrick Troughton) and his friends continue to battle against the world-domination plans of evil electronics wizard Tobias Vaughn (Kevin Stoney) and the Cybermen. When Vaughn turns against the Cybermen, it appears as if at least one aspect of the crisis is over. But even this turn of events might prove to be too little, too late if the Doctor is unable to stop the detonation of the Cybermen's bomb, which is capable of wiping out all life forms on Earth. Originally shown on December 21, 1968, "The Invasion, Episode 8" apparently no longer exists. ~ Hal Erickson, Rovi