Twenty-Two is the tale of a woman, in a hospital, who has a reoccurring dream of visiting a morgue downstairs. The plot is by no means new, it references a very, very old story.
Twenty-Two is markedly different from most other Twilight Zone episodes, in part due to the film quality (ironically video tape, used for budgetary reasons). The film quality greatly enhances the story, making the acting & score more surreal which makes the atmosphere even more unsettling. In fact, if not for the film quality (which gives everything an unusual realism), the episode might be utterly unremarkable in the context of the series. Of course, that'd be overlooking the stellar performances by Barbara Nichols and Jonathan "Doctor Smith" Harris with a humorous support by Fredd Wayne.
Even though the viewer is bound to know the ending, as this story has been retold many times in horror anthologies and in television, he is guaranteed to still be unsettled by the presentation.