The entire Scooby Doo series as a comedy is sketchy at best. The Scooby Doo Movies are some of the most entertaining of the series of Scooby due to the guest appearances,horrible animation, bad acting (as far as cartoons go), and plots from doom. So what is left? It is the return of Daphne as a damsel in distress. The usage of bondage as a selling point of this episode is so blatant that it is amazing that they bothered with a plot.
Daphne is bound and gagged a good percentage of the second half kidnapped by a Mr. Hyde want-a-be
who thinks she is Sandy Duncan. Daphne calls for help from a castle top after the villain grabs her. He then gags her japanese style. Anyway, if the damsel in distress aspect of Scooby Doo interests you then this is "the" episode. If you are looking for funny then let me tell you ... it ain't here.
See related damsel episodes: Which Witch is Which,Decoy for a Dognapper, What the Hex is going on?, Mystery Mask Mix-up, Menace in Venace, Big Scare in the Big Easy