The Mind of Evil is the second serial of the eighth season of the British science fiction television series Doctor Who, which was first broadcast in six weekly parts on BBC1 from 30 January to 6 March 1971.
The Third Doctor and Jo visit Stangmoor Prison to examine a new method of treating criminals, whereby negative impulses are removed from the mind using the Keller Machine.
Captain Chin Lee of the Chinese delegation is behaving strangely and attempting to heighten tension in relations with the United States.
However the Master is losing control of the Keller Machine, which contains an alien mind parasite that is dangerous even to a Time Lord, and forces the Doctor to help him contain its power.
The Master has come to Stangmoor to recruit the prisoners as a private army, and uses them to hijack a UNIT convoy transporting a deadly Thunderbolt nerve gas missile, which he intends to fire at the Peace Conference.
He tells Jo as he recovers, "Not long ago I saw an entire world consumed by fire..." This is a reference to the recent serial Inferno, also written by Don Houghton.
The hangar at the former RAF Swingate was used as the Master's hiding place for his deadly missile and Manston Airport was the base for the helicopter company providing the choppers and aerial footage in the series.
[4][5] This serial went so excessively over budget – primarily due to the use of the helicopter in episode 6 – that its director, Timothy Combe, was banned by Barry Letts from being considered for any subsequent Who work.
[8] David J. Howe and Stephen James Walker, in their 1998 book Doctor Who: The Television Companion, noted that the Master's plan was "so convoluted that it seriously lacks credibility".
However, they wrote that the story was an "undoubted success" because "the action is brought to the screen with such style and panache that the viewer hardly notices" the plot problems, with the direction and the alien menace being the highlights.
[11] In 2009, Mark Braxton of Radio Times gave The Mind of Evil four stars out of five, also praising the direction and Delgado's Master, though he noted there was a high body count.
[13] DVD Talk's John Sinnott rated The Mind of Evil three and a half out of five stars, writing that it kept a good pace and had "all of the elements that made Pertwee's run so enjoyable".