This may not be the best episode of the "Twilight Zone" series, but the least you can say is that it's original, compelling, and containing at least one highly effective and unforeseeable plot-twist. That's more than you get in most movies and TV-series, right?
Shortly before her marriage with the carefully selected - by her parents - nobleman Robert Blake, the stunningly gorgeous 18-year-old Anne Henderson goes out riding with her horse and gets the fright of her life when she's suddenly pursued by a hysterically shrieking woman in black. Any viewer can plainly see the woman is an older version of Anne, but the girl doesn't recognize herself. Only years and years later, Anne discovers she wasted a unique opportunity to warn her stubborn younger self about the wrong decisions she was about to make. Maybe - just maybe - try starting a calm and normal conversation next time, rather than acting like a deranged witch...
I know that many people, whose opinions I usually agree with, dislike this episode, but yours truly has a weakness for Sci-Fi/melodrama tales featuring time-traveling, inexplicable paradoxes, and the supernatural messing with the characters' minds. In other words, I liked it a lot and particularly appreciated the twist regarding the "wrong choice" as well as the visible agony and disappointment in "elderly" Anne's eyes and voice. Splendid performance by Diane Hyland, by the way! Rest assured, also, a combination of Rod Serling (creator), Richard Matheson (writer), and Elliot Silverstein (director) practically cannot fail.