505 Disaster - Puts the characters in very uncomfortable situations.
517 The Outcast - Puts the audience in a very uncomfortable situation.
523 I, Borg - An interesting ethical dilemma.
525 The Inner Light - The bittersweet feel of this story lingers long after. Fine acting by Stewart.

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Never attribute to malice what can be adequately explained by ignorance or stupidity.
Isaac Asimov