It is the future. The year 2017. Jimmy Neutron is now dating Cindy Vortex, his former rival. Jimmy, Carl, Sheen and Goddard are in the lab. Jimmy is finishing his new mutagen. Carl finds a test tube filled with pink liquid.
"Pepto bismol. I need this."
"No, Carl! That's my invisibility potion."
Suddenly Carl disappears.
"Whoa. That was cool." Sheen says.
Goddard lets Jimmy know that Cindy is approaching the lab. Jimmy lets her in. She greets him with a kiss.
"I'm glad that Carl isn't here. I can't stand that spaz." Cindy says.
Carl kicks Cindy in the butt.
"Ouch! What the heck is that? It happened when I called that dweeby Carl a spaz."
Carl kicks her again.
"Ouch! Who kicked me?"
"Carl? Where are you?"
"I'm invisible. You can't get me."
Suddenly Carl becomes visible.
"Carl, you're not invisible anymore." Jimmy says.
"Cindy, what I like best about you is your forgiving nature." Carl says.
Cindy slugs Carl hard in the stomach and makes him vomit.
"I'm going to leave now, Jimmy. I find it hard to face people when I've just been whooped by a girl."
When Carl leaves, Jimmy gives Sheen a job to do.
"Sheen, I want you to put these labels on my six huge containers. Put these three pesticide labels on my pesticide containers in the front and put these three mutagen labels on my mutagen containers in the back."
Suddenly Cindy pulls Jimmy aside.
"Are you sure that you should let Sheen label those containers?"
"Sure. Why shouldn't I?"
"He's an idiot."
"I doubt that even Sheen could mess this up."
Later as Jimmy finishes his work in the lab, three men arrive to collect the three large containers of pesticide.
"Take the three containers that are labeled pesticide."
As the men take the containers, jimmy goes to the house to have a snack. The next day he begins experimenting with his mutagen. He gives a dose to his hamster but instead of mutating, the hamster dies.
"That shouldn't have happened."
Suddenly Goddard alerts Jimmy that it's time for his date with Cindy.
"Thanks, Boy. I have to take Cindy to a movie."
Jimmy drives his hovercraft to Cindy's house. They kiss and she gets in and they drive off.
"I'm looking forward to seeing the bridges of Hadison County." Cindy says.
"That's a romance picture. I want to see the new JetFusion movie."
"You may want us to see the new JetFusion movie but we're not. We're seeing the bridges of Hadison County and that's final, Neutron."
Suddenly Jimmy's hovercraft is nearly knocked off the road by a large object.
"Jimmy, it's a fly and it's nearly twenty feet long. How did it get so big?"
"I'm not sure but I think we'd better get out of here."
"Look. It's a giant pill bug."
The pill bug rolls itself into a ball and begins rolling towards Jimmy and Cindy. As Jimmy drives down the road, the pill bug gets closer and closer. It smashes everything in its path. Jimmy soars into the sky and escapes the pill bug. Jimmy and Cindy then return to his lab.
"Sheen obviously put the wrong labels on the wrong containers. Yes, the pesticide is still here."
"I tried to tell you. Sheen is an idiot."
"I'd better call the company I sold it to."
Jimmy makes the call.
"What did they say?"
"So far it's only been distributed in Retroville. They're going to stop distribution. But the insects that have already been mutated will cause untold destruction. I must stop them."
"I'll have to try to make an anti-mutagen."
When Cindy leaves, Carl and Sheen come to the lab. They go driving through the city in hopes of catching a mutated insect.
"Why do you need an insect, Jimmy?" Carl asks.
"When I make my anti-mutagen, I'll need a mutated insect to try it on."
"Hey, there's a huge mud-wasp. Let's get it." Sheen says.
"It's too risky to try to catch an insect that stings. At that size, its sting would surely kill a person." Jimmy says.
"How about that fly above us?" Carl asks.
The huge fly rams into the hovercraft and knocks everyone out. As Sheen gets up, the fly grabs him and carries him off.
"It's got Sheen." Carl says.
Jimmy shoots the fly with his tranquilizer dart gun. Sheen and the fly fall on an air mattress that Jimmy inflates. They strap the unconsious fly to the hovercraft and take it to Jimmy's lab. When they carry it in the lab, they chain it to a table.
Jimmy begins mixing chemicals trying to create an anti-mutagen. He finishes it and sprays the fly but it has no effect on it.
"Well it's back to square one." Jimmy says.
Jimmy begins mixing chemicals again. Suddenly the fly breaks the chains and starts flying around the lab. Goddard trys to stop it but it knocks him to the floor. Jimmy quickly finishes his anti-mutagen. He sprays the fly and it returns to normal size.
"You did it." Carl says.
Jimmy then makes five hundred gallons of his anti-mutagen. He puts all of the anti-mutagen in his fire fighting hover craft. It's made to spray water on burning buildings. But he plans to use it to spray the mutated insects. Suddenly Goddard alerts Jimmy that Cindy is approaching his lab. He lets her in.
"What are you doing, Neutron?"
"I'm going to spray the insects with my anti-mutagen."
"I'm coming with you."
"No. It's too dangerous."
"I can handle it."
They all get in the extra large hovercraft and take off. As they fly fifty feet in the air, Jimmy begins spraying the insects.
"Look out!" Cindy yells.
A huge butterfly nearly rams the hovercraft. Jimmy then sprays it. After flying all over Retroville, Jimmy sprays every insect and returns them to normal size.
"You did it." Carl says.
As Jimmy lands, a huge hornet that Jimmy missed, stings Cindy. Jimmy sprays it. He then pulls Cindy out of the hovercraft.
"She's dying. Time is running out. I must save her fast. But how? Come on. Think. Think. Think."
Jimmy puts his brain to work.
"Brain blast! If I use my mutagen to increase her size, the sting won't be fatal."
Jimmy pours some mutagen in Cindy's mouth and steps back as she grows fifty feet tall.
"You do some amazing things, Jimmy." Carl says.
Cindy regains consiousness.
"I'm huge. This is cool."
Jimmy later returns Cindy to normal size and takes her home. He walks her to her door and kisses her. Nearly losing her, makes Jimmy appreciate her even more. Everything is back to normal in Retroville.