The Android Invasion

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

The TARDIS arrives on the planet Oseidon where the alien Kraals have created an exact replica of the English village of Devesham and its nearby Space Defence Station and populated it with androids in order to rehearse for an invasion attempt. A human astronaut, Guy Crayford, has been duped into collaborating with them.

The TARDIS travelson to Earth alone, and the Doctor and Sarah follow in Crayford's rocket, which is being used to carry the spearhead of the invasion force. The Kraals' chief scientist, Styggron, intends to release a deadly virus in order to weaken resistance to the forthcoming invasion.

On reaching Earth, the Doctor and Sarah try to convince UNIT troops at the Space Defence Station of the danger, but with the Brigadier away in Geneva, their attempts fall on deaf ears - Crayford is being hailed as a hero.

The Doctor uses the Station's transmitters to jam the control signals of the now active androids - including duplicates of himself, Harry Sullivan and RSM Benton - and prevents Styggron from releasing his virus. Styggron accidentally infects himself during a fight with the android Doctor and is killed.

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