The Mystery Inc. gang investigates the old Franken Castle after a gypsy fortuneteller warns them not to. Sure enough, the castle appears to be haunted by not one but three spooks: Count Dracula, Frankenstein's Monster and the Wolfman! And they all seem to have some kind of connection...
This episode contains examples of the following tropes:
- Artistic License – History: Someone writing a note in 1668 would not have referenced King Tut. King Tut only became significant when his tomb was discovered in 1922. His reign was extremely short, and he was otherwise almost forgotten.
- Bat Scare: Count Dracula supposedly has the ability to transform into a large vampire bat that swoops at the gang. In the end, it's revealed that it's just a stuffed bat on a wire Big Bob Oakley rigged as part of his charade, and Scooby rides on the wire to take a bite out of Shaggy's sandwich at the gang's picnic for his End-of-Episode Silliness gag.
- Blind Without 'Em: Velma accidentally loses her glasses (as per usual) when bumping her head on a table while crawling on the floor looking for clues. This leads to her making quite a few Blind Mistakes, including mistaking a torture chamber for a children's playroom, and she ends up tripping and falling into a barrel. Luckily Shaggy has been carrying her extra pair of glasses.
- Bullying a Dragon: Shaggy and Scooby see (what looks like) Frankenstein's monster asleep under a sheet on a lab table. What do they decide to do? Yank off the sheet and soak him with a hose.
- Cast as a Mask: The gypsy fortuneteller has the distinct witch-like voice of June Foray. She turns out to really be Big Bob Oakley, a man voiced by John Stephenson. Averted with Oakley's impersonations of Dracula, the Wolfman and the Frankenstein Monster, as John Stephenson voiced those as well.
- Disguised in Drag: Big Bob Oakley passes himself off as a female fortune teller to scare off the kids.
- Haunted Castle: The main setting of the episode.
- Hidden in Plain Sight: Big Bob Oakley is after the Franken family treasure—a cache of jewels worth a fortune. Despite searching for some time, he fails to find them. It turns out the gems are in an incredibly obvious spot: they're woven directly into a giant tapestry hanging on the walls of the Franken family crypt.
- Master of Disguise: Dracula, the Frankenstein Monster, the Wolfman and the gypsy fortuneteller all turn out to be criminal Big Bob Oakley, alias "The Actor" due to his mastery of disguise.
- Monster Mash: The monsters of the week are Count Dracula, the Frankenstein Monster and the Wolfman. With a twist in that they turn out to be the same Villain of the Week.
- Never Smile at a Crocodile: The moat surrounding Franken Castle has alligators, as per usual.
- No-Sell: Velma doesn't even blink as she tells off Dracula after he threatens the gang: "You stop that."
- Not Using the "Z" Word: The fortune teller says the castle contains dead, evil things. Furthermore, the word "vampire" only appears in the context of a vampire bat, and Shaggy and Scooby explicitly refer to Frankenstein's monster as a ghost at one point. It's possible this was done to appease censors over a vampire character.note
- Offscreen Teleportation: Big Bob Oakley proves remarkably adept at moving around at breakneck speed, even changing into three incredibly elaborate costumes while doing so. It's mostly justified as the castle is shown packed with secret passages of all kinds, but there are a few instances (such as his dressing as the Wolfman in a mad scientist's lab and then somehow getting under a sheet in his Frankenstein's monster garb without Shaggy and Scooby noticing) where it stretches credibility.
- Portrait Painting Peephole: A variant; a woman-shaped sarcophagus (later revealed to contain a secret passageway to a crypt) has eyeholes allowing the villain to spy on the gang in the torture chamber.
- Stranger Behind the Mask: Another instance in the series; the gang hadn’t met Big Bob Oakley, a.k.a. "The Actor", before, and so the police sheriff fills them in on who he is, and it's revealed that he had been the one disguising as all three monsters appearing at Franken Castle to scare people away.
- Took a Level in Badass: Scooby and Shaggy are at their bravest here—they swing to the rescue to help save Daphne, successfully trap the Wolfman thanks to Shaggy's ventriloquy skills and Scooby using some piano keys as fangs, and generally seem more confident than their usual Cowardly Lion selves.
- Vine Swing: When Daphne gets trapped on the other side of the moat, Fred lassoes one of the gargoyles and Shaggy and Scooby swing across to let down the drawbridge.
- You Meddling Kids: The standard version of the hero-blaming rant continues to evolve; Big Bob Oakley curses, "Yes, and I'd have gotten away with it, too, if it wasn't for these blasted kids and their dog."
