When a monstrous figure sneaks into the back of the Mystery Machine, the gang tracks him to the house of Dr. Jekyll, who tells them his suspicions that he's following in the footsteps of his ancestor and turning into Hyde's ghost. The gang investigates and finds evidence that someone is hiding something.
This episode includes examples of the following tropes:
- B-Movie Fan: Shaggy and Velma discuss a movie called I Was a Teenage Blob, which Velma laughingly calls corny.
- The Butler Did It: Subverted. All evidence initially seems to point to Helga the maid, but it turns out that evidence was planted by the actual bad guy, Dr. Jekyll, who kidnaps Shaggy when he finds a real clue.
- Cobwebs of Disuse: Shaggy and Scooby look in the attic and find that it's covered in cobwebs and dust. Amusingly, this condition is after Helga claims she cleaned it.
- Danger Takes a Backseat: Hyde sneaks into the back of the Mystery Machine while the gang eats dinner. He's only discovered when Velma asks Scooby to retrieve the blanket under which he was hiding. Velma and Shaggy also lampshade the trope with their B-Movie conversation.
- End-of-Episode Silliness: Scooby-Doo's demonstration of the suction cups Dr. Jekyll used during his robberies.
- Flat Scare: Fred, Daphne, and Velma all dress up as duplicates of Hyde to scare him as part of their trap, and while Fred and Daphne make scary moans and laughs, Velma sends Hyde running by simply tapping his shoulder and saying "Boo!"
- Full-Body Disguise: Besides the Ghost of Mr. Hyde's disguise, Fred, Daphne, and Velma manage to get identical costumes of Hyde to scare the main Hyde as part of their trap, with Velma being the smallest Hyde (naturally.)
- Heroic Dog: Despite his usual terror of ghosts, Scooby immediately begins hunting for Hyde after he abducts Shaggy and single-handedly rescues Shaggy from his clutches.
- Hoist by His Own Petard: Fred, Velma, and Daphne scare Hyde so badly he falls through his own trap door.
- The Jekyll Is a Jerk: In truth, Mr. Hyde was just a disguise for Jekyll, who was perfectly aware of his actions. Jekyll even tries to frame his maid for the whole thing and kidnaps Shaggy to do who-knows-what to him when he finds the suction cups Hyde uses to scale buildings.
- Never Smile at a Crocodile: Shaggy and Scooby have a run-in with an alligator while trying to escape Hyde.
- Nice Job Fixing It, Villain: Mr. Hyde's scheme would've continued to go unimpeded if he hadn't chosen to hide in the back of a van of a mystery-solving gang after his latest robbery.
- Non-Ironic Clown: Shaggy dresses as "Uncle Happy Time", a friendly clown hosting a kids' show, while he and Scooby are hiding in a television set.
- Red Herring: There were plenty of fake clues that seem to point Helga the maid as the culprit. The one true clue the suction cups eliminate her as a suspect. If she was the culprit, she wouldn't need them because she’s an ex-circus star famous for her "human fly" act.
- Scooby-Dooby Doors: The first time this happens in the franchise, involving the stretcher Shaggy is strapped to rolling through different doors in a hallway.
- Tempting Fate: While in the Mystery Machine, Shaggy and Velma's discussion about I Was a Teenage Blob has them agree how ridiculous a Danger Takes a Backseat scene was. Little do they know at that very moment...
- Wing Ding Eyes: When Shaggy and Scooby are running from an alligator in the swamp using oar-stilts, Scooby feeds Shaggy some Scooby Snacks. After swallowing the Snacks, the word "CHARGE!" flashes in each of Shaggy's eyes, and then he starts running faster.
