After a series of humiliating run-ins with Dash, the school bully, Danny uses his powers to get revenge and triggers the ghost of Poindexter, a kid who was shoved in his locker so many times he haunts it to this day. Danny must battle this ghostly defender of nerds and geeks, while proving he's not the bully Poindexter thinks he is.

Sam can barely contain her contempt for the "Miss Teenage Happy Princess" beauty pageant and its organizer, Dora Mattingly, when they descend on Casper High. She decides to enter the contest to make a statement about individuality, but makes a discovery instead: Dora Mattingly is the Dragon Ghost! Before she can get to the bottom of the mystery, she's inadvertently crowned Miss Teenage Happy Princess by its happy-go-lucky judge... Danny Fenton! When the tiara is placed on Sam's head, it magically transports her to a castle in the Ghost Zone, where she learns she's to be the bride of Dora's brother, the ghostly Prince Aragon. As Danny and Tucker head into the Ghost Zone to rescue Sam, she does her best to shake things up in the medieval ghost world she's stuck in.

The Fentons sell Fenton Works to the Guys in White who plan to destroy the Ghost Zone (unaware that Earth will be destroyed too) with a missile; meanwhile, Danny starts to let the rich life get a hold of him and jeopardize his friendship with Sam and Tucker.

Danny and Vlad’s game of revenge against each other begins with childish pranks, and, unfortunately for Danny, ends when Vlad decides to run for mayor of Amity Park! By overshadowing voters, Vlad wins in a landslide. The new mayor is eager to use his new power to make life as miserable as possible for Danny and his friends. He shuts down the Nasty Burger, outlaws technology, creates new school uniforms, and passes so many new laws in the name of “protecting the children” that Danny finds it impossible to go ghost.

As one of the weakest ghost in the Ghost Zone, the Box Ghost attacks with every "deadly box" he has in the human world, but is easily defeated by Danny. He then makes a plan: he will use "Pandora's Box", the most powerful box ever created, and will use the evil and deadly powers inside it to attack Amity Park. Now Danny must find the only one able to save the day: Pandora herself!

Danny's class goes to a camping trip with Mr. Lancer and Ms. Teslaff to an abandoned place which is seemingly haunted. Soon reports of monster sightings and missing students have the whole camp shook up. Monsters start showing up and disrupting the camping trip. To Danny's surprise, these monsters are ghosts working for Walker, on the hunt for Wulf. Now Danny must save his old friend and his class from Walker!