Two teenagers named Scott and Mary are on their way to Halloween party. When their car breaks down, they find themselves at the castle (and party therein) of Dr. Frankenstein, who quickly begins plotting to put Scott's brain into his monster. Unfortunately for him, all his other guests have their own plans for the young duo. Hilarity (and many catchy musical numbers) Ensue.
For the animated film based on the song, see Monster Mash (2000).
- Adaptation Distillation: The film only uses four songs from the original stage musical ("I'm Sorry the Bridge is Out, You'll Have to Spend the Night", "Play Your Hunch", "Eternity Blues" and "Things a Mother Goes Through") and uses the Monster Mash when the song was not present in the original showings of the stage version.
- Adaptation Name Change:
- Scott was called John in the original stage musical.
- The generic mummy from the stage musical is reinterpreted as a mummified Elvis Presley, with his servant Dr. Abdul Nasser reinterpreted as his fictional manager Hathaway.
- Adapted Out: Renfield and the grave robbers Montclair and Clairmont from the stage musical do not appear in the film version.
- Brain Transplant: Dr. Frankenstein plans to put Scott's brain into his monster's body.
- Country Matters: Count Dracula introducing his wife: "She's a count too, but she spells it differently."
- Curse Cut Short: Igor interrupts Dracula when he makes a crass remark.Dracula: Blow it out your—Igor: Ask me what time it is!
- Dracula: Count Dracula is one of the guests at Frankenstein's castle.
- The Film of the Song: A live action film loosely based on the song The Monster Mash.
- Frankenstein's Monster: The Frankenstein monster appears in the film, given that the film is partially based on the song The Monster Mash.
- Glad I Thought of It: Dr. Frankenstein takes credit for Igor's idea of giving the monster Scott's brain.
- The Igor: As one might expect, Dr. Frankenstein has a hunchbacked assistant named Igor.
- Monster Mash: We have Mad Scientist Dr. Frankenstein, his monster, hunchback Igor, Count Dracula and his wife Natasha, a werewolf and a mummy Elvis Presley.
- Mummy: Elvis Presley is established to have reincarnated as a mummy.
- The Musical: There are many songs in the film.
- Suddenly Speaking: At the end of the film, Frankenstein's monster turns out to be able to speak when he remarks "I'm surrounded by idiots".
- Vampires Hate Garlic: At one point, Dracula panics after being informed that he just consumed garlic.
- Voices Are Mental: When Igor tricks Dr. Frankenstein into switching brains with him, their voices switch with them.
- Working for a Body Upgrade: Igor pleads with Dr. Frankenstein to give him Scott's body after they put Scott's brain into the monster, as he is enamored with Mary and thinks having Scott's body will make her love him.