Vicky trashes Timmy's house and blames him for it. So when he is brought to Vicky's house to clean, Timmy decides to trash the place in revenge, but trouble ensues when Vicky and Tootie catch him in the act!
Mr. and Mrs. Turner leave Timmy under Vicky's care again, this time leaving to go visit the Scottish Festival, both of them are dressed in kilts. Seconds after they step out the door, they return to get Mr. Turner some underwear and notice the kitchen has been trashed. Vicky quite obviously caused the mess, but manages to lie and fool Timmy's parents into thinking Timmy is becoming a bad seed. The next day, Timmy is tied in heavy restraints ala Hannibal Lecter, he begs his parents that Vicky is blaming him for the mess she is causing, but then they laugh at this and leave. They return later when they realize they forgot to say goodbye to Timmy, but when they step in the house it has been trashed yet again. Since his parents are "nitwits" they believe Vicky's story, and he has to be babysat at Vicky's house, for an additional price of course, under her "Bad Seed Program".
Timmy arrives at Vicky's house, he is able to find it easily because it has a dark storm cloud hovering above it. He rings the doorbell, which plays out a funeral tune, and Vicky and Doidle greet him at the door. Vicky's Mom and Dad went out for dinner and she promised them the house would be "completely different". Vicky orders Timmy to clean her house and gives him a long list of chores. To be done in a French maid's dress. However, Timmy has other plans to prove to his parents that Vicky is the evil babysitter. He trashes the kitchen with a miniature tornado, the bathroom with green slime (Cosmo originally wanted to do so by eating a burrito, but Timmy pointed out they did not have the time to wait that long), and then he destroys Vicky's room by writing on the walls and having a frat boy party run wild through the room. However, Tootie catches him in the act of doing this when she overhears him say "What could possibly go wrong?".
Meanwhile, Vicky emerges from grinding her weapons in the basement and notices the destruction Timmy has caused. Vicky is afraid she is going to be in trouble with her parents for this, but sets off to punish Timmy first. Tootie is happy that Timmy trashed Vicky's room, and tries to kiss him while Cosmo and Wanda giggle at his squirming attempt to get away. Tootie hears the noise from under the bed and goes to inspect it, so Cosmo and Wanda poof into cats. Doidle finds them and chases them out of the room, causing them to drop their wands under the bed. Tootie finds the wands and thinks they were presents from Timmy. She takes the wands into her room and Timmy chases after her, he tries to get them back but Tootie realizes he will leave immediately after he gets them, so she throws the wands into a chest full of identical looking toy wands.
Vicky tracks Timmy down and chops down Tootie's door with an axe. Timmy tricks Tootie into thinking they are playing a game to hide from Vicky, and then locks her in the closet while he searches for Cosmo and Wanda's wands. Vicky corners Timmy, but when she hears her doorbell ring, she realizes she can blame the mess on Timmy. Cosmo finds the wands (or apparently he had them all along) and Timmy wishes the house back to normal. However, he is still in trouble with his parents because of his style of dress. Timmy also forgot to get Tootie out of the closet, which he nailed and boarded shut, but doesn't to be aware of this. As Cosmo and Wanda leave with Timmy, Cosmo notes "I have this feeling we're forgetting something or did we?". The episode then ends with Tootie crying to Timmy that she needs to use the potty before suddenly remarking "Oops! Now I don't!".