Scooby-Doo and the gang travel to Atlantic City, where Fred enthusiastically takes them to see The Brancusi Circus. They arrive to find that the circus does not open until tomorrow, but decide to look around when they notice that the front door is unlocked. Whilst searching, they meet a man who is pursuing a werewolf that has intruded into the circus. The werewolf attacks the gang, but is eventually scared off by Velma, using a spotlight. The man thanks the gang and introduces himself as Marius Brancusi, the ringleader. Marius inherited the circus from his uncle last year and has been working to modernize it. He informs the gang that the werewolf they had encountered has been shadowing the circus for a few months, has scared off many of his artists, and has stolen jewelry wherever they are. He even suspects that the werewolf might be one of his own artists. Velma notices that this incident alludes to a case during the 18th century, in Ingolstadt, where a werewolf named Hans collected a combination of jewels which enabled him to change into a werewolf at any time. After the gang tells Marius that they solve mysteries, Marius hires them to go undercover as circus performers.