The War Machines was the tenth and final story of season 3. There were several companion cast changes in this story — Dodo Chaplet, played by Jackie Lane, left, while Polly and Ben Jackson, played by Anneke Wills and Michael Craze, joined. Ben and Polly join Dodo herself, Barbara and Ian in the fact that they accidentally entered the TARDIS and then later joined the First Doctor as companions.
The TARDIS arrives in London in 1966 and the First Doctor and Dodo visit the Post Office Tower. There they meet Professor Brett, whose revolutionary new computer WOTAN (Will Operating Thought ANalogue) can actually think for itself and is shortly to be linked up to other major computers around the world — a project overseen by civil servant Sir Charles Summer.
It transpires, however, that WOTAN considers humans to be inferior and believes they should be ruled by machines. Exerting a hypnotic influence, it arranges the construction of War Machines — heavily-armed, self-contained mobile computers — with which to take over the world.
These prove more than a match for troops, but by establishing a magnetic force field the Doctor is able to capture one of them, which he then reprograms to destroy WOTAN. Dodo, now back in her own time, decides to remain on Earth. The Doctor enters the TARDIS alone, but Brett’s secretary Polly and her merchant seaman friend Ben Jackson follow him inside just before it dematerialises.
Find out more at tardis.wikia.com.
The Doctor stands up to the War Machines on the Doctor Who YouTube Channel.