The Twilight Zone: Season 5, Episode 21 - ProjectFreeTV

5 - 21: Spur of the Moment

An engaged heiress is scared by an older woman wearing all black, on horseback.  Her fiance jokes that it was an attempt to get her to call off her upcoming wedding. However, it appears that an old beau may be more successful in getting the young woman to call off the wedding than the woman on the black horse.