"Nightmare as a Child" is 29th episode of The Twilight Zone, first broadcast in April of 1960. It starred Janice Rule and Shepperd Strudwick, and also had a small part for the then-child actress Morgan Brittany, who would star in Dallas as an adult.
Janice Rule plays Helen Foley, a schoolteacher living a seemingly peaceful life. She comes out from work one day to find a small girl sitting in the foyer to her apartment, and invites her in for hot chocolate. Their friendly talk takes an ominous turn, but the girl must depart suddenly because there is another visitor, a man named Peter Seldon (Shepperd Strudwick) who seems to have some connection to Helen, and who might have taken part in a childhood incident she can't quite remember. The little girl then returns and gives some hints to Helen, finally revealing what the audience probably guessed a while ago. The episode then reaches a sudden and dramatic conclusion.
This episode is notable for several reasons. First, while two previous episodes had featured female characters, this is the first episode that passes the Bechdel Test, with two female characters conversing. This episode has a lot of conversation, and in terms of both action and scenery is minimalistic, even by the standards of the Twilight Zone. But the lack of obvious action doesn't distract from the episode's ability to produce fear: this is the first episode where I've physically recoiled out of fright.
The psychological nature of the threat also has dimensions that might have been unapparent to both the creators and the audience. While Helen's fear comes from persecution by a man who has stated financial motives, their is a subtext that he is preying on her for other reasons. In a comment that seems particularly strange to me in 2014, he even says that he had a "crush" on her when he knew her as a child. Perhaps the word doesn't mean now what it meant then, but it seems to be a strange comment for an adult to make about a child, especially at a time when issues of sexuality were so tightly controlled on television that married couples had to be shown sleeping in separate beds. Especially since this episode deals with repressed memory, it is easy to read the drama going on as about something that not only the characters, but the creators, were not totally aware of. Although this particular interpretation might not work for everyone, the psychological nature of the drama makes this episode full of possible meanings.