It is a wonderful afternoon in the city of Perry MI where friends and family can be found.
Two kids Charlie "Chris" Christopher and his friend Mary Marigold were just living in this wonderful place. They have lived normal kid lives and they did normal kids things like playing one their videogame consoles, getting into trouble with grown ups, eating sweets to spoil their dinners, causing mischief everywhere, and play at the playground.
They have friends as well: Daphine Von Denver, a vain, sometimes, spoiled girl who not only loves Charile but is Mary's rival, Velma Edwards, a bookish tomboy who is Mary's friend and a great science class partner. George Rangerfield, a frenemy who sometimes act as a school bully and a rival to Charlie. Bob "Bobbie" Rodgerfield, is a prankster and practical joker who is both Charlie and Mary's best friend who secretly likes Velma.
Normally, these two were normal kids but this time things were different. No one could quite explain it but it was interesting to say the least. For starters, their brown hair (though Mary's is darker than Charlie's) has slowly become more of a green color. Stranger still, Charlie's eyes are orange and while Mary's hair is green her eyes, however, are in a dark purple.
While some kids are all tuckered out, these two are always full of energy and rarely need sleep. The most strange thing is that they can't eat junk food at all...and can only guzzle down vegetables and fruits. Now while the first two are considered strange to anyone, the last one would be a blessing to any parent, all of this is considered really odd to a kid.
Daphne thinks that Charlie is still handsome while Mary is semi-cute, Bobbie still thinks of them as friends (despite sometimes joking poking fun at them), George thinks their weirdos (but then again bullies always think that), Velma, however, has always believe that they are the next step in evolution for the human race. Speaking of which, Velma has orange-colored eyes and green too. For a while, the kids were not at all concerned about this and their parents didn't seemed worried about it either. Little did they realize that it was all about to change real soon.
While watching TV one day in the basement, Velma is working on a new invention: a telephone that can fit into your pocket. The kids all think its a crazy idea...phones, as everyone knows, are too big to fit in your pants pocket and they only remain on tabletops or attached to telephone poles. They still think that her idea of a small record-like device to replace floppy discs was just as silly.
Before long, Chris feels a strange yet familiar feeling in his shorts and is not happy as they slowly become a orange color. Annoyed, Chris then decides to head to the other end of the basement with the others soon follow only for Chris to be in more pain. Now Mary is in pain as well, although she believes this didn't start happening for her until just the past two weeks.
As the kids unzip their shorts, two large pants (a large carrot, and a beanstalk-like vine) emerge from in between their legs only to grow and stretch ouit until it reached a bag full of something brown. As it took root in the bag, Chris and Mary both become humanoid balloonish plant entities; Chris becomes a comically large and wide barrel chested carrot thingy while Mary becomes a purple rotund eggplant person.
Although the other kids are rather stunned, both Chris and Mary have no idea what to do but escape but when they head outside they find that things have change and they see no one in the basement but Chris and Mary. Leaving the basement, they're greeted by more folks who appear to be normal...except they want to give them medicine, so they escape. They decide to find Velma at her house.
While they getting there, they encounter giant venus-flytrap monsters trying to catch them but they barely dodge them with their new powers but then more flower monsters then show up to cause trouble for them, but they either fight them or escape them.
Upon arrival, though, they find that Velma's dad, Dr. Samuel Edwards, who knocks the kids out and takes them hostage. Awaken later, both Chris and Mary then see Velma not only strapped to a gurney but is inflating and is changing color while her father menacing glances at her. After he leaves, the kids free themselves only to see Velma become...a large pumpkin person.
Once freed, Velma quickly explains that her dad has Lanchanophobia (fear of veggies) due to her uncle dying by choking on a carrot and her dead aunt's veggie allergies. She also tells them the her dad's evil boss, Mr Pendleton, is the culprit. Together, the three decide to find the others.
Now they must fight more plant creatures and even mushroom monsters that are chasing them as well. Soon, they must fight a guardian who is preventing others from passing to another part of the city: Lansing MI.
Even once in Lansing, they must fight more plant creatures as Chris tries to make sense of everything but Mary insist that he must focus if they are to survive. Despite constant captures, and some dead turns, they are finally on the right track. After fighting another guardian, they finally arrive at Daphne's house and head upstairs.
It isn't long before they find Daphne sitting on a weird pump that is inflating her...causing her to become a balloonish turnip person. Because she's so big that she can't move, the others must get Daphne out of the house. With their friend in tow, they look for the others while fighting the monsters. Daphne is still getting bigger but is able to fight nonetheless and they head to East Lansing. Once there, they find out that George is also exposed to a balloonish pumpkin that is turning him into a beet-like person as well.
They also see...Bob as a odd pumpkin-like snowman who looks at them funny, but when Chris asks what's wrong, Bob explains that...Mankind has been dead for four decades.
The End?!?