Intro: One of the dangers of time travel is the temptation to change the future. One would think a member of The Doctor's own race would know better. But one would be mistaken as we will perceive when we meet "The Time Meddler."

Outro: What could we do if it became apparent that the Earth would soon plunge into the Sun? We could build a huge spaceship and travel to another world. The problems would be unimaginable, but not insoluble, as we will discover next Sunday night at 11 when "The Ark" begins its voyage. [source: ChicagoEpguides]