While visiting Washington, a rainy day drives the gang to the Smithsonian for some indoor sightseeing. Unfortunately, Scooby goes missing, resulting in them being trapped in the museum overnight. Naturally, it turns out that a trio of ghosts are haunting the Smithsonian: Benedict Arnold, Major Andre, and William Demont.
This episode includes examples of the following tropes:
- All for Nothing: The Spirit of '76 had attempted to steal a bunch of new dollar bills from the United States Treasury. Unfortunately, the printing room they had drilled into was filled with money that hadn't received their serial numbers, treasury seals, or the Treasurer's signature yet, meaning it was all completely worthless.
- Artistic License – History: The John André ghost is dressed like an American soldier, when André was a British officer.
- Chekhov's Gun: The gang hear a mysterious, very loud noise in the basement. It turns out to be the demolition equipment the villains are using to break into the United States Treasury next door.
- Closed Circle: The guards lock the doors at a particular time every night, and the engaged lock won't open until a certain time in the morning. Therefore, the gang can't leave the museum.
- "I Can't Look!" Gesture: Played for Laughs. When the gang stumbles on the undressed dummies of Benedict Arnold, Major Andre, and William Demont, Daphne covers her eyes and quips that they shouldn't be like that in mixed company.
- Red Herring: Mr. Grumper is unfriendly and leaves wet footprints (which the gang find suspicious given that it suggests he's been outside the museum). He isn't the culprit.
- Rain, Rain, Go Away: The episode begins with the gang lamenting the rain making a wash of their trip. Then Shaggy comes up with an idea: they can see the Smithsonian, which is indoors.
- Tandem Parasite: The ghost of William Demont hitches a ride on the tandem bike Shaggy and Scooby use for an escape. After Shaggy announces that he thinks they lost him, the ghost taps Scooby's shoulder.
