The Films plot:

Young filmmaker and scientist, Victor Frankenstein lives with his parents and dog, Sparky in the suburban city of New Holland. Concerned with his son's isolation, Victor's father encourages him to take up baseball and make achievements outside of science. At his first game, Victor hits a home run, and Sparky, pursuing the ball, is subsequently killed by a car.

Inspired by a demonstration of the effect of electricity on dead frogs, a depressed Victor digs up Sparky's corpse, creates a makeshift laboratory in the attic, and successfully reanimates Sparky with lightning. Seeing a cat, Sparky escapes from the attic and explores the neighborhood, recognized first by Edgar, Victor's hunchbacked-classmate. Edgar blackmails Victor into showing him how the reanimation worked, resulting in the two reanimating a goldfish (which turns invisible). Edgar brags about the fish to their classmates, sparking their interest in reanimation.

Victor's parents discover Sparky in the attic, causing him to flee. Joined by Victor, the family search for the dog while the classmates invade the lab, discovering Victor's reanimation formula. Each classmate going their separate way perform their own experiment. Nassor revives his hamster Colossus at the cemetery, who bears a resemblance to the Mummy. Toshiaki's dead turtle Shelly becomes a huge Gamera-like monster. Bob dumps a package of sea monkeys into his pool, who transform and chase him into the streets. Edgar breaks into the school and brings back a were-rat. Weird Girl's experiment takes a wrong turn when she accidentally mutates the bat intended for the experiment and Mr. Whiskers into a vampire cat. The animals wreak havoc in the town. Although each pet is eventually defeated, Mr. Whiskers carries off Elsa van Helsing, Victor's love interest, to the town's windmill. The townsfolk blame Sparky for the monsters and chase him inside the windmill, setting it ablaze. Sparky rescues both Victor and Elsa from the burning windmill to the town's approval, only to be pulled back inside by Mr. Whiskers. The cat is staked through the heart with a falling rafter just as the windmill crushes Sparky to death.

As reward for his bravery, the townsfolk gather to revive Sparky with their car batteries, reanimating him once more. Sparky awakens and reunites with his own love interest, Persephone, Elsa's Bride of Frankenstein-style poodle.