In the conclusion of the four-part story "The Tenth Planet," Ben (Michael Craze) at last figures out the Cybermen's weakness. For the moment, it appears as though the earth is saved from the alien villains. But the story isn't quite over yet, as proven when Ben and Polly (Annika Wills) come face to face with the "new" Doctor Who. Written by Kit Pedler and Gerry Davis, Doctor Who: The Tenth Planet, Episode 4 first aired on October 29, 1966. Alas, except for a few fragments of the crucial sequence in which William Hartnell relinquishes the role of the Doctor, this episode no longer exists. ~ Hal Erickson, Rovi