The film begins with Vincent Price who plays the Vampire Erasmus walks around looking for a little midnight snack. Before you know it he is nibbling on John Carradine. Although Price is famous for the many horror movies he has been, this is the only film where he actually plays a vampire. After their awkward first meeting they politely introduce themselves to one another. Erasmus declares that Chetwyn-Hayes is his favorite horror author and then invites him to come along to a monster club that he frequents.
The monster club is filled with all sorts of creatures and ghouls, many who you can tell are wearing silly monster masks. But its the vibe of the club that hooks you in. Immediately you hear a band called The Viewers sing the theme of the film called, Monsters Rule O.K. Then Erasmus begins to explain the hierarchy of monsters to Chetwyn-Hayes from coolest poster I have even seen.
Erasmus explains to his new human friend, "We have the primate monsters: vampires, werewolves and ghouls. Now, a vampire and a werewolf would produce a werevamp, but a werewolf and a ghoul would produce a weregoo, and a vampire and a ghoul would produce a vamgoo. A weregoo and a werevamp would produce a shaddy. Now, a weregoo and a vamgoo would produce a maddy, but a werevamp and a vamgoo would produce a raddy. Now, if a shaddy were to mate with a raddy or a maddy the result would be a mock. Frankly, that's just a polite name for a mongrel."
There are four stories told while at the monster club as well as musical sequences in-between each story. The main story is about Erasmus and his human friend, Mr. Chetwyn-Hayes, which bookends the other three story. The first story Erasmus shares is about a Shadmock and warns Chetwynd-Hayes that "oh, you should see the results of a Shadmock's whistling. The story begins when a young lady named Angela and her greedy boyfriend begin looking to find ways of stealing and making an easy buck. Angela ends up landing a job with a reclusive man named Raven, who happens to be a Shadmock. Although Angela finds him both terrifying and repulsive, she agrees to work for him in order to get closer to his money. The end is shocking and tragic when the Shamock releases his infamous whistle.