The TARDIS arrives in London in November 1963, where the Seventh 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 that the Doctor's grand-daughter Susan attended, while a human military unit led by Group Captain Gilmore is attempting to resist their incursions. The Imperial Daleks eventually capture the device, and 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 Doctor, whereby the Hand of Omega utterly destroys the Dalek home planet of Skaro, and then returns to destroy their forces orbiting Earth.