The Evil of the Daleks

From http://www.bbc.co.uk/doctorwho/classic/episodeguide:

The TARDIS has been stolen by antiques dealer Edward Waterfield, who lures the Doctor and Jamie into a trap. They are transported back to Waterfield's own time, 1867, where his daughter Victoria is being held hostage by the Daleks to ensure his cooperation.

The Daleks force the Doctor to monitor Jamie's performance of a test - the rescue of Victoria - with the supposed intention of identifying the human factor: the special quality possessed by humans that enables them always to defeat the Daleks. The Doctor, having succeeded in this task, implants the human factor into three test Daleks - with the result that they become friendly and playful!

Everyone is transported back to Skaro where the Doctor discovers that the Daleks' true aim has been to isolate the Dalek factor - the impulse to destroy - and implant it into humans. The Emperor Dalek informs him that his TARDIS will be used to spread the Dalek factor throughout all time.

By a ruse, however, the Doctor is able to infuse many more Daleks with the human factor. A civil war breaks out between the two Dalek factions and they are apparently all destroyed. As Waterfield has been killed during the course of the action, the Doctor offers Victoria a place aboard the TARDIS.

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