William Hartnell had been playing the part of the Doctor for three years (1963-1966). However by mid-1966 the work schedule and the first stages of the illness – "Arterioscierosis" had caused his health to grow steadily worse. And in the end it was clear that he had to leave the show for not only was it getting harder for Hartnell to act but also the illness has caused him to fluff his lines more than usual and was therefore damaging the show.

If Doctor Who was going to survive, it would mean that another actor would have to take over the role. Could the public be persuaded that it was the same character?

Producer, Innis Lloyd, chose Patrick Troughton for the role from a list which included Ron Moody (up again for the 4th Doctor) and Sir Michael Hordern.

For this task it was decided that the Daleks will make a reappearance to launch the Second Doctor's stories and to show the public that while the Doctor has changed, nothing else about the show was any different.

The setting for this story was Vulcan, now famously known as the home of Star Trek's Mr Spock. This story was made and shown before the name of Spock's planet was mentioned in Star Trek.

A clever idea was that the Doctor wasn't sure exactly who he was and also caused his two companions - Ben (Michael Craze) and Polly (Anneke Wills) to be suspicious of the new arrival. But over the story, the Doctor & his companions sees who he is and about the Power Of The Daleks.

The Time: Far into the future
The Place: An Earth Colony, Planet Vulcan

The new Doctor, leading a puzzled and frightened Ben and Polly, lands the TARDIS on Vulcan, where he takes the identity of a murdered Examiner (official investigator) from Earth to examine a strange capsule that had been found in one of the mercury pools on the planet surface.

Inside the capsule, the Colony's scientist and the Doctor finds three dead Daleks and despite the Doctor's warnings the Colonists activate the Daleks which claim that they wish to become servants to the Colonists.

Only the Doctor and his friends know the evil intelligence inside the Daleks but the Colony isn't without its own problems. The security officer has plans to take over the colony, rebels to the Colony's leader are massing for an attack and everybody is eager to use the Daleks for their own ends....

But the Daleks have different ideas and have their own agenda.......