The story continues where the previous book left off, with George and Harold running away from Tippy Tinkletrousers. As they are running away, the book explains that what happened was something that was not supposed to happen as Tippy and his Robo-pants were not supposed to appear at the point when George and Harold were about to be arrested as they actually came from the future.
The book then explains something called 'The Banana Cream Pie Paradox', which explains that going back to the past and changing something will remain its changed way in the present. Meanwhile, the story switches to the timeline of what will happen if Tippy Tinkletrousers did not appear, where George, Harold and Mr. Krupp to jail. George and Harold are sent to the Juvenile Hall while Mr. Krupp was sent to the Piqua State Penitentiary. The 3 were actually framed and mistaken for Evil George Beard, Evil Harold Hutchins and Captain Blunderpants's evil antics causing chaos in the town of Piqua.
One autumn afternoon, Tippy (who is also a prisoner from the fourth book) is tasked to build a statue of Warden Gordon Bordon Shmorden who is chief jailer of the prison, Tippy does the task but instead builds "a giant robot suit". Krupp notices Tippy and he remembers and confronts him for what happened the last time when he shrunk the school and make everyone change their names. However Krupp does not remember that he as Captain Underpants was the one to put a stop to Tippy's reign of terror that day.
On the day Tippy presents his robot suit to Gordon Shmorden, he reveals his work and climbs on to the suit and freezes everyone in his way (the same suit used at the very end of the eighth book). Tippy then grabs Mr. Krupp and forces him to spill the information of Captain Underpants and to give him the information of George and Harold whereabouts. Tippy soon finds George and Harold and puts Mr. Krupp down, wanting information of Captain Underpants. Krupp picks on them telling them they they were in a lot of trouble. Seeing that they were in danger of Tippy plotting his revenge, George and Harold act fast and snap their fingers at Mr. Krupp who turns into Captain Underpants. Tippy then realizes that Mr Krupp was Captain Underpants all along and Captain Underpants gets chased, while Tippy is unsuccessfully trying to freeze him, soon he accidentally freezes his robotic legs and as a last resort, time travels to five years into the past. Captain Underpants flies down in confusion wondering where he might have gone.
The story switches to George and Harold as kindergarteners who have a hard school life due to the fact that Kipper (a school bully and Mr. Krupp's nephew) bullies them along with his friends and that Kipper can easily get out of a bad jam by calling for his uncle. George and Harold find a way to stop Kipper by using an incomplete prank of the ghost of 'Wedgie Magee', which scares Kipper and his gang, so much that they run out of the school.
On Monday morning, Kipper gives a 5 dollar bill to Donny Shoemeyer and promises to return all the money he stole from him. Elsewhere, Kipper's friends are passing out money to the kindergartners and doing good deeds for them. Kipper and his friends eventually gave back all the money they stole and never picked on anyone ever again. George and Harold would later call off the vengeful wrath of Wedgie Magee after they were certain their enemies were truly reformed. However it is revealed that what happened was what was supposed to happen not what actually did happen. As it turns out, Tippy had time traveled to right when Kipper and his friends were running out of the school.
It then goes back to when Kipper and his friends were running out of the school. At this point, Tippy and his Robo-pants appear. Due to Tippy's dialogue to Kipper and his friends while it was still dark, they mistakenly thought that it's the haunted pants of Wedgie Magee and become insane. Tippy then travels four years into the future. Unbeknownst to Tippy, his actions led to Kipper and his friends being sent to a mental health institute and the police to immediately suspect Mr. Krupp for what happened to the sixth graders (in both the original and changed timeline, Mr. Krupp was unintentionally beaten up by Kipper and his friends while escaping from the school due to a blackout). The Cops show up and blame Mr. Krupp. This eventually led to Mr. Krupp being fired which means in a few yrs he would not be hypnotized by the 3D Hypno Ring into becoming Captain Underpants.
Tippy then time travels back to the present time, thinking that kids five years from the past were weird. However, as Mr. Krupp was hypnotized when George and Harold were in the 4th grade, a universe is created where Captain Underpants never existed. Tippy arrives to a present destroyed and overrun by giant evil zombie nerds. After learning of the changes that have happened in the present, Tippy realizes the terrible mistake he made and becomes determined to return time to normal and save Captain Underpants. However, Tippy immediately gets squashed by George and Harold, who are now giant zombies nerds. What remains left of Tippy is a red squishy stain.
The Adventures Of Dog Man
The comic begins with a police guy whose partner is a special trained police dog named Greg. They are professionals on catching criminals. One day, he and Greg spotted a bomb, but it was too late to defuse it. Then they got transported to the Hospital via Ambulance. The doctor announces that Greg's body is dying and the Cop's head is dying too. Then the nurse had a great idea: that he will cut off Greg's head and sew it on the Cop's body. The doctor accepted the idea and they held a big operation. It was successful and everyone called him "Dog Man." Dog man is the best of all cops because he sniff criminals with his nose, hear crimes with his ears, and punch criminals with his fist. But he had one mortal fear: vacuum cleaners. Petey, the world's most evilest cat, saw Dog Man's weakness so he invented the evil vacuum robot. The robot stole all the money from the bank and Dog Man came to stop it but the vacuum was chasing him. The robot chased Dog Man until he reached to the corner. Dog Man knew it was death time for him until the plug for the robot got unplugged. Dog Man then destroyed the robot and followed the cord. The cord lead to Petey's hideout and arrested him. Then Dog Man celebrated the victory by drinking some none alcoholic wine.
The Curse Of Wedgie Magee
The comic starts with this kindergartner named Wedgie Magee who always got picked on by the bunch of bullies. The bullies also gave him wedgies and stole his money. One day, he couldn't take it anymore so he went to see a Gypsy Lady. Wedgie said that he gets wedgies all the time and she said that he is going to give him a special Potion that will help him. She was supposed to give him the Anti-Wedgie Potion, but when she forgot her glasses, she gives him a Voodoo Ghost Potion instead. She gave Wedgie the instruction that when the bullies come by to give him a wedgie, he has to pour the potion onto his pants. The next day the bullies came by to gave him a wedgie, and he poured it onto his pants. The pants dissappeared and it became a ghost. Nobody was scared and they are laughing in hysterics. Then he died of embarrassment. On that very night when Wedgie Magee died, his pants came back for revenge. He ate the first bully on his way home from school, ate up the second bully while he was eating dinner, and ate up the third bully when he was in bed. After that, his pants are laid to rest, but he will be back to people who are mean to Kindergartners. At the back of the comic book, there is a bonus section page explaining to the reader or Kipper and his friends the ways he could get cursed and how to undo it. Here are the reasons:
- You start acting all weird and stuff
- You want to play with Dolls, Dresses, and Bracelets.
- You get ectoplasm and spiders on your stuff.
- Awesome food like pizza tastes all hot and burns your mouth and stuff.
- Your armpits get all burned and stuff.
The only way to undo this curse is must undo all the bad stuff you did and never pick on nobody ever again.
- Mr. Krupp's full first name is revealed to be Benjamin.
- This book reveals a lot of George and Harold's past and how they met among other things.
- The Coming Soon section of the 8th book shows that this book has a scene involving Tippy chasing Captain Underpants, George, Harold, Sulu and Crackers on a Tyrannosaurus Rex in the Cretacious Period. The final version of this book doesn't have this scene, but the tenth book shows that the gang will go to the Cretacious Period, and a redrawn version of that scene is used in chapter 7 of book 10.
- The Everything Except Fabric Softener Store makes a third appearance in the series. It previously appeared in the fifth book and the seventh book.
- The eleventh chapter is called Furious George. This is a reference to the book parody that Dav Pilkey was initially going to make before he abandoned it and went to work on the first Captain Underpants book (because his girlfriend thought it was too offensive to be published). Even though Furious George was never made into a book, Dav Pilkey liked the flipping action violence so much that he dubbed it Flip-O-Rama and incorporated this into the Captain Underpants books and the Ricky Ricotta books.
- The Flip-O-Rama chapter's title is a parody of Indiana Jones and the Temple of Doom.
- The little boy and his mother make a return appearance in this book. Their last appearance was in the fourth book which was Professor Poopypant's debut appearance.
- In the 8th book, it was implied that Jerome Horwitz Elementary School did not have a school nurse. In this book it's revealed that the school does have a school nurse as Kipper and his friends had to spend two hours in the nurse's room with ice packs on their tongues since they were burned by the ghost chili peppers. However it's possible that the school stopped having a school nurse at some point after George and Harold's kindergarten times.
- This book's intertwining story of George and Harold's past is by far the longest story in any of the books shown thus far. Most backstories are relatively short while the main part of the storyline takes up most of the book. The main part of the storyline in this book is relatively short in comparison to most books as the parts explaining what actually did happen and where Tippy went and what his actions did are explained in the beginning of the story and close to the end. The remaining parts of the story are about George and Harold's past.
- This book by far is the longest book in the series, with a page total of 304.