[@BangoSkank]No need to know much more than the bare basics. In classical D&D, the party would be pulled from their traditional fantasy locale by various means to a pseudo-Transylvania ruled by the human-turned-vampire Count Strahd Von Zarovich, and would usually have to either defeat or disable him in order to escape home. The original module features different story points randomly chosen by what's depicted in-game as a tarot card reading, which helped sell its replayability. It's also infamous for Strahd's domain of Barovia being essentially real-world in that magic and nonhumans are almost unheard of beyond the vampire himself.