theme park attraction. Vicki stows away aboard the Dalek ship and witnesses them create an android replica of the Doctor (Edmund Warwick), programmed to kill the TARDIS crew, which is dispatched on arrival on the hostile jungle world of Mechanus. Vicki reunites with the Doctor, Ian, and Barbara, but a fight ensues between Ian and the real Doctor once the robot duplicate appears, claiming to be the original. When the robot Doctor mistakenly refers to Vicki as his granddaughter Susan, Barbara realises and the real Doctor disables his doppelgänger. As the Doctor and his companions venture into a metal city above the jungle, Mechonoids imprison them with shipwrecked human astronaut Steven Taylor (Peter Purves). Under the cover of the Daleks attack on the city, the Doctor and his companions escape. Upon discovering the Dalek time machine and considering it more reliable than the TARDIS, Ian and Barbara persuade the Doctor to help them operate it to return to London in their own time. Upon arriving in London, 1965, Ian and Barbara set the time machine to auto-destruct. The Doctor and Vicki witness a conversation between Ian and Barbara on the Time-Space Visualiser; the Doctor says that he will miss them, and he and Vicki depart in the TARDIS. Production Conception and writing Following the success of the Daleks in their introductory serial The Daleks (1963–1964) and its sequel The Dalek Invasion of Earth (1964), writer Terry Nation was quickly commissioned to write a third serial by new story editor Dennis Spooner, with whom he was old friends due to their history of comedy writing. Nation's original story pitch was scrapped for unknown reasons, and he was instead commissioned to write a six-episode Dalek serial, tentatively titled Doctor Who and the Daleks (III), around mid-December 1964. Nation submitted a five-page synopsis on 10 January 1965 to producer Verity Lambert, aware of the fact that it would be a more expensive production than typical. In Nation's synopsis, the story was known as Dr Who (Segment: Dalek Three) – The Pursuers; a few months later, it became The Chase. Nation wrote the scripts between writing episodes of The Saint (1962–1969). In the first episode's script, Nation suggested that the footage of the Gettysburg Address could be borrowed from the 1962 film How the West Was Won. Nation's scripts required little editing from Spooner, though he was too busy to undertake rewrites regardless. Original