Materializing in contemporary London the doctor,and his companion Dodo experiences an unusual magnetic sensation throughout his body. His investigation leads him to a newly completed tower which houses a new logical mainframe computer called WOTAN. It's creator Professor Brett intends for the device to be networked around the world for peaceful and defense purposes. However the doctor senses something amok when the computer recognizes him and the meaning of the term TARDIS. The Professors secretary Polly Wright offers to take Dodo to her favorite nightclub where they meet up with the Naval officer Ben Jackson,who has been trying to get Polly to notice him and defends her from a palaver. What they do not yet know is that during this time,the Professor and his compatriot Krimpton have been co-opted by WOTAN and are now taking instructions from it. Dodo is soon influenced in the same manner,via a phone call at the club. Sir Charles Summer,promoting the massive WOTAN project to the government body,soon finds a number of mysterious goings on as the Professor and all of his compatriots continue to exhibit secretive behavior.
Polly is abruptly summoned to to Sir Charles' office when the doctor recovers Dodo,who he realizes has been attempting to get him under WOTAN'S control under the influence of hypnotic suggestion. While deprogramming her Ben,whose come to pick up Polly for a date,notices the secretary has already left the building. The doctor sends him to investigate and he discovers she,as with the Professor for whom she was once employed is now working for WOTAN. The computer has deduced human beings can no longer effectively run the planet. And is deploying it's own creators to create unstoppable war machines to destroy them. While her friendship with Ben forces the hypnotized Polly into helping him escape,he goes on to inform the doctor who sends the military to destroy the war machines but they are unsuccessful. In the end it's up to the doctor,who creates a magnetic field that he uses to reprogram the machines to destroy WOTAN and liberate it's captors from it's control. Before departing in his TARDIS,Ben and Polly return to send him the message Dodo has elected to remain on Earth. When they find him walking into a police box (actually the TARDIS),Ben produces a key that slipped out of the doctors pocket that he intended to return to him,and he and Polly enter the TARDIS just as it is about to take off.
In terms of story,setting,pacing and the characterizations this is one of the most engaging and enjoyable stories from the William Hartnell era Doctor Who. For the first time,he's portrayed as something of a man of action rather than merely a scientific detective. It's also a story very much ahead of it's time. With the advent of computerization about to occur,this story was very telling in many people's fears of the machines we ourselves programmed taking over our lives. Also this story takes along with that concept a perhaps implied anti fascist and communist message of human beings forced into serving a greater power based solely in logic and pragmatism. Even though your never sure if the characters of Ben and Polly will stay with the doctor until the very end,these two lovable and very helpful characters really have the affect of endearing themselves to the heart of the viewer. Though the underrated Dodo Chaplet exists the TARDIS in the story,the show gain two new (if now sadly under-represented in terms of surviving Doctor Who stories" in Ben and Polly.