Do you remember going to sleepovers as a child and, in the near pitch black of their bedroom, seeing the barest outline of your friend's face, except their eyes were wide open staring back at you? This episode is kind of like that, except funny and not scary.
It's "Scooby-Doo & Scrappy-Doo" and Shaggy who are under the impression that Daphne might be a vampire, specifically one of the San Francisco Bay variety. Will their suspicions win out, forcing them to devise ways of slaying their former companion? Probably not, but you'll have to listen to find out!