Out beyond the far reaches of space, an unknown planet explodes sending a strange meteorite across the galaxy, heading towards Earth. Meanwhile, Susan Murphy of Modesto, California is going to be married to news weatherman Derek Dietl. Just before the ceremony, she is hit by the meteorite and its energy causes her to glow green and grow to enormous size with her hair turned white. She is tranquilized by the military and awakens in a top secret Area 51 that houses monsters of which the public are ignorant. She meets General W.R. Monger, the U.S. Army officer in charge of the facility, and her fellow monster inmates: Dr. Cockroach PhD, a mad scientist who became half-human, half-cockroach after an experiment; B.O.B. (Benzoate Ostylezene Bicarbonate), a brainless, living mass of blue goo as a result of a food flavoring mutation; Insectosaurus, a massive mutated bug standing 350 feet in height, and the Missing Link, a prehistoric 20,000 year old fish-ape hybrid who was thawed from deep ice by scientists. Susan herself has been renamed to Ginormica.
Susan Murphy (a.k.a. Ginormica) and the Monsters are now working with the US government as special ops. So when an alien presence is detected in Susan's hometown of Modesto, California -- right before Halloween -- the team is dispatched to investigate. Everything appears normal, right down to the jack-o-lanterns peering out from every doorstep and windowsill. But when Halloween arrives, those innocent-looking carved pumpkins reveal themselves for what they really are mutant aliens. The altered pumpkins then start to implement their fiendish plan to take over Earth. The Monsters are there to combat the mutant gourds and try to smash their wicked scheme!
Inspired by DreamWorks Animation's 2009 blockbuster feature film, this new series follows the further adventures of the beloved monsters- B.O.B., the gelatinous blob without a brain; Link, the prehistoric fish-man; Dr. Cockroach, the half-man/half-insect mad scientist; and Susan (aka Ginormica), the incredible growing woman-as they learn to adapt to a new world filled with bizarre aliens.
After a mutant alien pumpkin explodes on the Murphy's carrot garden, zombie carrots start attacking the immediate area, and it's up to the Monsters to save the night again.