While attending an Other Realm amusement park, Sabrina runs into her shifty evil twin, Katrina, who's set on sabotaging Sabrina's life.

After she learns Hilda and Zelda won't be home for Halloween, Sabrina decides to throw a party at their place- and soon regrets the decision when she must repair the love of two monsters Frankenstein & Bride of Frankenstein when Roxie get's in the way of their meaningful relationship. Meanwhile Salem stalks a college girl and Hilda Zelda's outfits may not seem to be all that for the galaxy opening.