This episode has a lot of potential but I think the whole is less than the sum of its parts because the main plot is the weak link - Number 6 foils the plan of John Sharp's Number 2 and turns it against him far too easily.
It begins well, with scenes showing us the tools and techniques the Village uses to enforce conformity among the villagers. The supposedly impartial committee, which is of course controlled by Number 2 from behind the scenes however much he publicly denies it, declares Number 6 "unmutual" (a fabulous term and the most memorable part of the episode) and he is ostracised by the villagers.
It goes wrong when we see the next step beyond being declared unmutual - "instant social conversion," an operation to remove aggression from a person rendering them permanently incapable of rebellion.
But Number 6 is too valuable to the Village for something permanent like this to be done to him, so the operation is faked using drugs with the intention that Number 6 will think he has been 'converted.'
But he sees through this really easily, and swaps his drugged tea with Number 86's. While she is drugged and suggestible Number 6 hypnotises her into turning the tables on Number 2 and declaring him to be unmutual at a public meeting.
I think it may be the case that the writer knew what he wanted to achieve, he just didn't quite have the skill to pull it off. Number 2 being hoist by his own petard allows Number 6 to win against him with a sense of poetic justice, but the execution of this plot element is just not up to the high standard I would expect of The Prisoner as a whole.
The real strength of this episode are in its themes - the pressure to conform in society and the subversion of otherwise benevolent groups by corrupt elements, both of which are as relevant today as they must have been in 1967.
The stand-out scenes for me are when Number 6 defies the committee and the 'social group' they send him to, for which he suffers the consequence of being declared unmutual. And, of course, that chilling word itself...
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