In the conclusion of the four-part story "The Brain of Morbius," Sarah (Elisabeth Sladen) manages to persuade the Sisterhood of Karn that the Doctor (Tom Baker) does not pose a dire threat to their existence. Spared from execution, the Doctor tries to prevent evil scientist Solon (Philip Madoc) from reviving the brain of infamous Time Lord criminal Morbius. Alas, he is too late, and the episode comes to a pulse-pounding conclusion as the Doctor matches wits -- and powers -- with the most dangerous and deadly Time Lord in all history. Originally telecast on January 25, 1976, "The Brain of Morbius, Episode 4" was written by Terrance Dicks. ~ Hal Erickson, Rovi