Dr. Frederick Frankenstein (Gene Wilder) is a physician lecturer at an American medical school and engaged to the tightly wound socialite Elizabeth (Madeline Kahn). He becomes exasperated when anyone brings up the subject of his grandfather, the infamous mad scientist. To disassociate himself from his forebear, Frederick insists that his surname is pronounced "Fronkensteen."
Six-year-old Ana is a shy girl who lives in the manor house in an isolated Spanish village on the Castilian plateau with her parents Fernando and Teresa and her older sister, Isabel. The year is 1940, and the civil war has just ended with the Francoist victory over the Republican forces. Her aging father spends most of his time absorbed in tending to and writing about his beehives; her much younger mother is caught up in daydreams about a distant lover, to whom she writes letters. The entire family is only ever seen together in a single shot towards the end of the movie, there is no discussion. Ana's closest companion is Isabel, who loves her but cannot resist playing on her little sister's gullibility. Teresa writes to her past lover while she seems to stare out the window at the old house where Ana will find the republican soldier: "Little but the walls remain of the house you once knew, I often wonder what became of everything we had there." This supposes the house has a history for her, and implies the escaped republican soldier who will run straight to this now empty and crumbling house and hide in it may have been her lover.
On a stormy night, Percy Bysshe Shelley (Douglas Walton) and Lord Byron (Gavin Gordon) praise Mary Shelley (Elsa Lanchester) for her story of Frankenstein and his Monster. Reminding them that her intention was to impart a moral lesson, Mary says she has more of the story to tell. The scene shifts to the end of the 1931 Frankenstein.
In a European village Henry Frankenstein, a young scientist, and his assistant Fritz, a hunchback, piece together a human body, the parts of which have been collected from various sources. Frankenstein desires to create human life through electrical devices which he has perfected.
Lawrence Talbot (Lon Chaney, Jr.) is making an urgent call from London to a Florida railway station where Chick Young (Bud Abbott) and Wilbur Grey (Lou Costello) work as baggage clerks. Wilbur answers the phone and Talbot tries to impart to him the danger of a shipment due to arrive for the "McDougal House Of Horrors" (a local wax museum) which purportedly contains the actual bodies of Count Dracula (Béla Lugosi) and the Frankenstein Monster (Glenn Strange). However, before he is able to warn Wilbur, a full moon rises and Talbot transforms into a werewolf, who proceeds to destroy his apartment while Wilbur is on the line. Wilbur, thinking the call is just a prank, hangs up and continues on with his work day. Immediately thereafter, the actual Mr. McDougal (Frank Ferguson) shows up to claim the shipments and, fearing them damaged when Wilbur and Chick mishandle them, demands that the crates be delivered in person so his insurance agent can inspect them.
The story opens in the 1950s, after the Korean War; it has been more than a decade since James Whale, director of Frankenstein and Bride of Frankenstein, has retired. He lives with his long-time housemaid, Hanna, who loyally cares for him but disapproves of his homosexuality. Whale has suffered a series of strokes that have left him fragile and tormented by memories: growing up as a poor outcast, his tragic World War I service, and the filming of The Bride of Frankenstein. Whale slips into his past, and indulges in his fantasies, reminiscing about gay pool parties and also sexually teasing an embarrassed, starstruck fan who comes to interview him. Whale battles depression, at times contemplating suicide, as he realizes his life, his attractiveness, and his health are slipping away.
Part one
Victor Frankenstein is a man training as a doctor, engaged to Elizabeth Fanshawe. After Victor's younger brother, William, drowns, Victor renounces his belief in God and declares that he would join forces with the Devil if he could learn how to restore his brother to life.
Victor Frankenstein (played by Barret Oliver) is a young boy who creates movies starring his dog, Sparky (a Bull Terrier, whose name is a play on the use of electricity in the film). After Sparky is hit by a car, Victor learns at school about electrical impulses in muscles and is inspired to bring his pet back to life. He creates elaborate machines which bring down a bolt of lightning that revives the dog. While Victor is pleased, his neighbors are terrified by the animal, and when the Frankensteins decide to introduce the revitalized Sparky to them they become angry and terrified.
Years after the events of the last film Baron Wolf von Frankenstein (Basil Rathbone), son of Henry Frankenstein (creator of the Monster), relocates his wife Elsa (Josephine Hutchinson) and their young son Peter (Donnie Dunagan) to the family castle in the eponymous village. Wolf wants to redeem his father's reputation, but finds that such a feat will be harder than he thought after he encounters hostility from the villagers. Aside from his family, Wolf's only friend is the local policeman Inspector Krogh (Lionel Atwill) who bears an artificial arm, his real arm having been "ripped out by the roots" in an encounter with the Monster as a child.
In the aftermath of the death of Dracula's wife Martha (Jackie Sandler) at the hands of an angry mob, Count Dracula (Adam Sandler) designs and builds a massive five-star hotel in Transylvania in which to raise his daughter Mavis (Selena Gomez) and to serve as a getaway for all the world's monsters.
Young filmmaker and scientist Victor Frankenstein lives with his parents, Edward and Susan Frankenstein, and his beloved dog, Sparky, in the quiet town of New Holland. Victor's intelligence is recognized by his classmates at school, his somber next-door neighbor, Elsa Van Helsing, mischievous, Igor-like Edgar "E" Gore, obese and gullible Bob, overconfident Toshiaki, creepy Nassor, and an eccentric girl nicknamed Weird Girl, but communicates little with them due to his relationship with his dog. Concerned with his son's isolation, Victor's father encourages him to take up baseball and make achievements outside of science. Victor hits a home run at his first game, but Sparky, pursuing the ball, is struck by a car and killed.
The Monster Squad is a society of young pre-teens who idolize classic monsters and monster movies and hold their meetings in a tree clubhouse. Club leader Sean (Andre Gower), whose five-year-old sister Phoebe (Ashley Bank) desperately wants to join the club, is given the diary of legendary monster hunter Dr. Abraham Van Helsing (Jack Gwillim), but his excitement abates when he finds it is written in German. Sean, his best friend Patrick (Robby Kiger), and the rest of the Monster Squad visit an elderly man, known as the "Scary German Guy" (Leonardo Cimino), actually a kind gentleman, to translate the diary. When the Monster Squad wonders how the German man is so knowledgeable about Van Helsing's battle with monsters, he wryly comments that "he has some experience with monsters" and his shirt sleeve briefly reveals a Concentration camp number tattoo.
Scooby-Doo, Shaggy, and Scrappy-Doo are on their way to a Miss Grimwood's Finishing School for Girls, where they have been hired as gym teachers. Once there, however, they find that it is actually a school for girl ghouls. The pupils include Sibella, the daughter of Count Dracula; Elsa Frankenteen, the daughter of Frankenstein's monster, Winnie, the daughter of The Wolfman; Phantasma (usually called Phanty for short), the daughter of a phantom, possibly The Phantom of the Opera; and Tanis, the daughter of The Mummy - all parodies/tributes to the Universal Monsters of the 1930s-40s. Other residents of the school are a floating white hand; an octopus, who is the school's butler; Legs, a spider that helps with the upcoming volleyball match; Miss Grimwood, the headmistress; and her pet dragon Matches (who dislikes Scooby at first, but later becomes friends, and has a strong friendship with Scrappy). Shaggy and Scooby want no part of this at first, but eventually they agree to stay as teachers.
Velma gets a call from Cuthbert Crawley, a lawyer for Velma's family who tells her that she's inherited her great uncle's property and castle in Transylvania. Velma turns the offer down, replying she wants nothing to do with her uncle, puzzling the gang. Mr. Crawley understands, revealing the curse over the estate. He says that if anyone gets too close to the Baron legacy, then what they love the most will be destroyed. As they head outside, Fred hears a noise from the Mystery Machine, then it explodes and a mysterious character with a mask appears. Crawley reveals that it's the ghost of the Baron, Velma's old ancestor. The remains of the machine explode again, with words saying stay away from Transylvania, but Fred declares that is where they're going to find the person responsible for destroying the Mystery Machine, saying this time "it's personal".