The Tenth Planet
At a tracking station on the South Pole, radars pick up signals from a new planet heading into orbit, which drains the energy from a space shuttle, and then starts to do the same to the Earth. Its inhabitants are revealed to be the Cybermen, who need the energy to carry out their plan to turn humans into their own kind. A first invasion force is defeated, and after The Doctor manages to overcome a second, Mondas (Earth’s long-lost twin world) is blown up. The experience seems to age The Doctor, and on returning to the TARDIS, Ben and Polly can only watch as he collapses and starts to regenerate
Attack of the Cybermen
Whilst narrowly avoiding a collision with Halley’s Comet in the TARDIS, The Doctor and Peri encounter a distress call emanating from London, Earth in 1985. The Doctor decides to investigate…In central London, a gang of diamond thieves, led by ex-Dalek agent Lytton, plan to enter their target building via the sewers. But once down in the darkness, things start going wrong, for lurking in the underground shadows are the Cybermen… When The Doctor and his companion Peri are captured by the Cybermen, they are caught up in a complex scheme to dramatically alter history as the Cybermen try to prevent the destruction of their original home world, Mondas.
Attack of the Cybermen was the first episode of season 22 and The Tenth Planet was the third story of season 4 and William Hartnells last story