Doctor Who: The Androids of Tara, Episode 4 on AllMovie

In the conclusion of the four-part story "The Androids of Tara," the Doctor (Tom Baker) and Romana (Mary Tamm) are still mired in a medieval power struggle on the arborial planet Tara. Hoping to arrange a wedding between Prince Reynart (Neville Jason) and Princess Strella, then kill Reynart and wed the Princess himself in order to ascend to the royal throne, Count Grendel of Gracht (Peter Jeffrey) has forced Romana to pose as Strella, her exact double (both roles are played by Mary Tamm). As intrigue piles upon intrigue, the Doctor wonders if he will ever be able to retrieve the fourth segment of the Key to Time, thereby restoring the balance between Good and Evil throughout the universe. Written by David Fisher, "The Androids of Tara, Episode 2" first aired on December 16, 1978.