The kids search a museum investigating a legend that when the moon is full the "Black Knight"--an ancient suit of armor originally from England--comes alive.
After running their boat aground on an island during one foggy evening, the group investigate a ghost that keeps trying to scare them off the island and out of the spooky castle located there.
When several top show dogs are stolen, the kids go after a $500 reward offered by one of the dogs owners--and it is up to Scooby-Doo to be a decoy for the dognappers.
Scooby and Shaggy find a violin case filled with counterfeit money. The gang's search for clues to this mystery leads them to a puppet theater--and a sinister puppet master.
A ghost clown is haunting Mr. Blackstone's circus, and all the acts are quitting. It's up to the kids to stop the clown and find out if he's really a ghost.
A gypsy fortune teller warns Scooby and the gang not to visit Franken Castle. They go anyway and find themselves chased by a werewolf, a vampire and a Frankenstein Monster.