In the conclusion of the four-part story "The Creature From the Pit," the title character -- actually an ambassador from the planet Tythonus -- harbors a terrible secret which will profoundly affect the fate of the planet Chloris. The Doctor (Tom Baker) eventually discovers that Chloris is slated for destruction by a neutron star, a disaster that will, of course, also affect him. Once the villainous Lady Adrasta (Mary Frances) is disposed of, the Doctor hopes to be able to save the residents of Chloris from their predetermined annihilation. Written by David Fisher, "The Creature From the Pit, Episode 4" was originally telecast on November 17, 1979. ~ Hal Erickson, Rovi