The story begins with the kinky school troublemakers, George Beard and Harold Hutchins, two boys who are known by almost every one of their teachers as disruptive and rude. George and Harold love to play pranks on the helpless kids and teachers at Jerome Horwitz Elementary School. They are also known schoolwide for the comic book series that they create and sell on the playground, known as "The Adventures of Captain Underpants", their favorite super hero. They have many enemies (all of them being the faculty teachers). But the one who despises them most is the school principal, Mr. Krupp. Mr. Krupp hates them, their pranks, and especially the Captain Underpants comics. He vows to get them one day ("one day very very soon" he claims).
One day, the school's football team, the Jerome Horwitz Knuckleheads, is having their biggest game of the year against the Stubinville Stinkbugs. Before the game even starts, the football players, cheerleaders, and band players already experience countless problems with their equipment. Apparently, someone sabotaged the whole game. After many more pranks, the game had to be called off. As the players walk away, we see George and Harold crouching beneath the bleachers, laughing. Of course, they were the ones who did it all. They believe they won't get in trouble for it since they assume there is no proof the teachers can claim to prove they did it.
The next day, George and Harold hear an announcement over the school's intercom. They are wanted in Mr. Krupp's office. Once inside, He shows the two boys that he set up video cameras all over the school, and had caught every single one of George and Harold's pranks on tape. After the tape is over, everyone is silent for a while. Then, George gets the courage to speak up and asks what Mr. Krupp is going to do with the video. Mr. Krupp thinks about it, and decides that he should show it to the school board or George and Harold's parents, but he ultimately decides to show it to the football team so they can see who ruined their big game. George and Harold beg and plead Mr. Krupp to spare them as the football team will kill them for the rest of their lives if they do find out the truth. Mr. Krupp decides not to show the video, as long as George and Harold promise to follow his conditions. Mr. Krupp takes out a stack of paper with countless chores and behavior rules for George and Harold to follow. He also mentions they MUST follow the list exactly; otherwise he will show the video to the football team. The next day, George and Harold spend their entire day doing chores for Mr. Krupp, behaving nicely, and completing stacks of extra homework.
After taking in the homework, George states he has an idea that can could get them out of this situation. George reveals that he had bought a 3-D Hypno-Ring which they could use to make Mr. Krupp hand them the video and forget that this whole mess ever happened. After 4-6 weeks of back-breaking labor, George and Harold finally get the ring via the mail. After purposely making themselves late for chores and school, Mr. Krupp gets them into his office and demands where were they this morning. George and Harold state they were going to show the new ring they got. George then uses the 3-D Hypno Ring to hypnotize Mr. Krupp into handing over the incriminating video. Harold replaces it with one of his little sister Heidi's Boomer the Purple Dragon sing along videos. As they look in the cabinet on what Mr. Krupp had confiscated from the boys and other people over the yrs, they discover some good stuff including the Captain Underpants comics they wrote from the previous yrs. They began to reminisce the comic books by reading. Hours later, they realized it was getting close to lunch time as they were preparing to leave that noticed Mr Krupp still in a trance, so they decided to wait and play around. They then begin fooling around with the ring hypnotizing Mr Krupp thinking he is a monkey then later a chicken. And then lastly, they get an idea after looking at the comic and George hypnotizes Mr. Krupp to act as if he were the Amazing Captain Underpants. Mr Krupp began removing his toupee and clothing and takes of the curtain tying it to his neck and he is seen dressed like Captain Underpants yelling the battle cry "Tra La Laaa!". George and Harold look at him and began laughing hard to their distress. As they stopped laughing to take one more look at him, they saw he was gone. They then heard him outside doing the battle cry again and as they look out the window they saw Mr Krupp dressed as Captain Underpants running outside into the city of Piqua. Mr. Krupp, as Captain Underpants, takes the role seriously and departs to fight crime. George and Harold were shocked knowing that they didn't give a command to Mr. Krupp to fight crime. So they took their skateboards and a few items out the cabinet to help save the principal.
George and Harold flee the school searching all over the city to where Captain Underpants might have gone off too. They later find him at a bank. Captain Underpants confronts two bank robbers, and orders them to "Surrender! Or I will have to resort to Wedgie Power!" The bank robbers fall down in hysterics and are apprehended by the police. The sheriff isn't amused by Captain Underpants acting heroically so he gave a command and the police officers begin to arrest Captain Underpants too, but George and Harold whisk him to safety on their skateboards.
Suddenly, the crystal shop next door explodes, as two robots walk out of it, carrying a very large crystal. Captain Underpants tries to stop them, but his cape gets caught on their van. George and Harold grab onto Captain Underpants's feet, as he is dragged to an old, abandoned warehouse. A boy and his mother are at the bench waiting for the bus as the boy sees them passing by but the boy's mother didn't believe him.
Captain Underpants then crashes through the door of the warehouse while George and Harold slam into the back of the van. There they discover the evil Dr. Diaper, a mad scientist resembling a baby. As Captain Underpants was in plain view to Dr. Diaper, the robots capture and tie him up. When the coast became clear, George and Harold peak into the hole in the door (Captain Underpants created this when he crashed into it) to see what is going on. The witness Captain Underpants tied up in a chair with the robots beside him. The villain explains that he plans to use the crystal as part of his Laser-Matic 2000 to blow up the Moon, destroying every major city on earth, so that he can take over the planet.
George uses a slingshot to toss fake doggy doo-doo between Dr. Diaper's feet. Dr. Diaper is terribly embarrassed, thinking that he has had an "accident". When he departs to change his diaper, George and Harold incapacitate the robots and untie Captain Underpants. They pull the self-destruct lever on the Laser-Matic 2000 thinking that will turn it off.
Dr. Diaper, enraged at the destruction of the Laser-Matic 2000, his robots, and the foiling of his plan to take over the world, aims his Diaper-Matic 2000 ray gun at George, Harold, and Captain Underpants.
Captain Underpants shoots a pair of underwear at Dr. Diaper. The underwear covers Dr. Diaper's face, which renders him incapable of defending himself. Before the building exploded, the boys ask the Captain, "Where did you get that extra pair of underwear?" and the reply was, "What extra pair?" while Captain Underpants wore a barrel over himself (stating that Captain Underpants used the underwear he wore against Dr. Diaper, thus completely naked at that time). After the warehouse explodes and George, Harold, and Captain Underpants escape, they send Dr. Diaper to the police station and tie him to a nearby pole, so that he can't escape and the police can arrest him..
George, Harold, and Captain Underpants return to Mr. Krupp's office. They give Captain Underpants Mr. Krupp's clothes along with an extra pair of underpants to dress up like Mr. Krupp, so that nobody in the school would recognize him. Captain Underpants them gives them the meanest look to them like the boys asked him to do to look like Mr. Krupp. The boys try to figure out how to return Mr. Krupp to his normal self, but they've lost the instruction manual for the 3-D Hypno-Ring. They try several times to hypnotize Captain Underpants back into Mr. Krupp, but the methods do not work. As a last resort, George tries dumping water on Mr. Krupp's head. It works, and Mr. Krupp returns to his angry self, resolving to give the video to the football team after all though George and Harold are surprisingly very happy to see Mr. Krupp again. George finds the instruction manual to the 3-D Hypno-Ring in his shirt pocket, but he and Harold throw it away as they believe they do not need it anymore. As it turns out, the team enjoyed the Sing-A-Long video so much that they change their name from the Knuckleheads to the Purple Dragon Sing-A-Long Friends.
George and Harold go back to their goofy ways with nothing that is threatening to their lives. Unfortunately from this point on, whenever anyone snaps their fingers, Mr. Krupp transforms into Captain Underpants. Ms. Ribble is then shown snapping her fingers after George and Harold disrupt the class with their jokes, Mr. Krupp who was passing by with a cup of coffee unfortunately hears the sound of fingers snapping and drops his cup of coffee being in a trance, becomes Captain Underpants again and runs out of the school to fight crime. Harold and George hear his battle cry and both look outside to see that Captain Underpants has return once again. Much to their surprise, both respond to this with "Oh No!" and "Here we go again!" respectively as they thought it was over with Captain Underpants, it wasn't. The adventure was only just beginning.
Hypno Ring MisunderstoodAnd another thing, after Mr. Krupp is "watered," the ring instructions are found in George's shirt pocket. After being thrown away, you can read on the back of the instruction manual, "WARNING!" "Whatever you do, don't pour water on anybody's head when they are in a trance! This will cause the hypnotized person to slip back and forth from trance to reality whenever they hear they hear the sound of fingers snapping." Despite this, the boys were able to de-hypnotize their teacher "Ms Ribble" through the ring with no problems although considering how they were panicking they may not have thought of trying to use the method used in the fifth book.
- Early printings of the book have " An Epic Novel by Dav Pilkey" instead of "The First Epic Novel by Dav Pilkey" and the "Little Apple" logo on the cover.
- Ms. Ribble and Mr. Meaner didn't have names in this book until Captain Underpants and the Attack of the Talking Toilets.
- The comic in the book has the same name as this book's title, but Dr. Diaper and his robots weren't seen.
- "The Inedible Hunk" is a parody of The Incredible Hulk.
- "Dr. Diaper" is a parody of Doctor Doom.
- "Weird Al" Yankovic is mentioned in this book when Mr. Krupp says the kids played "Weird Al" songs full blast for six entire hours on the intercom. Funnily enough, "Weird Al" performs the theme song for Captain Underpants: The First Epic Movie.
- "Boomer The Purple Dragon" is a parody of Barney the Purple Dinosaur.
- In the North American version, the villian is called Dr. Diaper, but in the European English version, he is called "Dr. Nappy" ("Nappy" is the European term for Diaper).
- The 1991 sci-fi novel Fallen Angels is referenced surrounding the 3D hypno-ring advertisement.
- This is the only book where there is no recap comic at the beginning of the book before the first chapter begins. This is because this is the first book of the series.
- Captain Underpants in reality has no idea on who his alter ego "Mr. Krupp" is.
- On the comic book, Captain Underpants didn't have his cape on, while he was throwing underpants at the Inedible Hunk.
- Another version of this book, the Full Color version, was released on August 2013. As the title states, the illustrations within the book are printed in full color, instead of being black and white.
- On the about the author page, It said "When Dav Pilkey was in school, he always getting into touble for pulling pranks, cracking jokes, and making silly comic books." The "r was missing on "trouble.
- George Beard
- Harold Hutchins
- Benjamin Krupp as Captain Underpants (character)
- Dog Man (Mentioned only)
- Timmy the Talking Toilet (Mentioned only)
- The Amazing Cow Lady (Mentioned only)
- Edith Anthrope (Indirect mention)
- Superman (Appeared in comic(s))
- Unidentified bank robber (comics) (Appeared in comic(s))
- Wonder Woman (Appeared in comic(s))
- Batman (Appeared in comic(s))
- Unidentified cafeteria ladies (Appeared in comic(s))
- Inedible Hunk (Appeared in comic(s))
- Unidentified boy I (comics) (Appeared in comic(s))
- Elementary school principal (Appeared in comic(s))
Creatures and Species
- United States of America
- Unidentified city (comics) (Appeared in comic(s))
Organizations and titles
Vehicles and vessels
Weapons and technology
- George Beard's tie
- Sign-switching gag
- Rose (Mentioned on sign)
- Padlocked crate of pencils, pens, and paper
- Toilet (Mentioned only)
- Wedgie Power
- Bench (Appeared in comic(s))
- Boxer shorts (Appeared in comic(s))
- Stinky Taco Surprise Day
- Trash can
- Benjamin Krupp's toupee