Remembrance of the Daleks

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

The TARDIS arrives in London in November 1963, where the Doctor and Ace discover that two rival factions of Daleks - one loyal to the Dalek Emperor and one to the Dalek Supreme - are seeking the Hand of Omega, a powerful Time Lord device that the first Doctor hid there during an earlier sojourn on Earth.

The Daleks are focusing their search around Coal Hill School - the school that the Doctor's grand-daughter Susan attended - while a military unit led by Group Captain Gilmore is attempting to resist their incursions.

The Doctor tries to keep Gilmore and his team out of harm's way while the two Dalek factions battle each other for control of the Hand. The imperial Daleks eventually overpower those led by the Dalek Supreme and capture the device.

The Dalek Emperor is revealed to be Davros, now with only the last vestiges of his humanoid form remaining. The Doctor begs him not to use the Hand, but is ignored. However, this is just the final ruse in a complex trap laid by the Time Lord to defeat his old adversaries.

The Hand vaporises the creatures' home planet, Skaro, by turning its sun into a supernova, and then returns to destroy their forces orbiting Earth. The Doctor confronts the Dalek Supreme and causes it to self-destruct by convincing it that it is the sole surviving member of its race.

22 out of 137 (16.1%) raters say this story requires a previous story.