Captain Underpants and the Big, Bad Battle of the Bionic Booger Boy, Part 2: The Revenge of the Ridiculous Robo-Boogers: Summary
Captain Underpants and the Big, Bad Battle of the Bionic Booger Boy, Part 2 starts just a few moments after part 1 ends. George, Harold, Principal Krupp, Melvin, and Sulu are being chased by the bionic boogers. They are almost caught when Sulu swallows the boogers and spits them heroically into space.
Everyone soon realizes that Principal Krupp and Melvin have exchanged bodies. To keep them apart, they are given the names Mr. Melvin and Kruppy the Kid. Kruppy the Kid convinces Mr. Melvin to make a new machine to change them back. Mr. Melvin agrees, but explains that it will take 6 months. Because of the long amount of time, George develops an idea to build a time machine instead to bring them back to the original Combine-o-Tron 2000, and they all agree it is a much better idea since that will take only one or two days.
Fingers are snapped and Kruppy the Kid turns into Captain Underpants. The boys let Melvin in on the secret, and Melvin devises a plan to keep Captain Underpants’ superpowers once they are returned to their bodies.
Melvin tells George and Harold to create a comic book with him as a character while he builds the time machine. In the comic, a barrel of nuclear waste is accidentally dumped on a field of cotton. Once the cotton is harvested, it is made into underwear, and Melvin’s mother buys him a pair on sale. The underwear grows into a monster overnight and in the morning, war is declared. Captain Underpants defeats the monster and takes Melvin to jail.
Melvin is angry the next day when he finds out the comic does not depict him as cool. He shows George and Harold the time traveling machine and warns them to be careful, because if it is used more than once without letting it recover, something bad will happen. He gives them a device that erases short term memory and a Combine-o-Tron decoy to replace the real once with. The boys go back in time two days and get the machine.
Later, George and Harold return to the library and use the time machine a second time to travel backwards in time and capture a Qutraleoatulus that Harold calls Crackers. They return just as the librarian is trying to steal the Combine-o-Tron and memory eraser to take to the police. At the sight of the dinosaur, the librarian is convinced it is all a dream. The boys send the dinosaur back to his own time and erase the librarians memory.
Kruppy the Kid is meanwhile getting into trouble as Captain Underpants. He is found by Mr. Melvin and they return to their original bodies.
The robo-boogers land on a spaceship on Uranus. There is a brief cameo of the Talking Toilets from the second book. They ride the spaceship as it returns to earth and begin to cause distruction. Captain Underpants tried to stop them and then realizes his super powers stayed with Melvin. Melvin will not help unless George and Harold change the comic.
Captain Underpants fight the robo-boogers anyway. Together with the help of George and Harold, they discover the boogers are killed when they are hit with oranges. They kill one by throwing oranges at him, but trick the other two with an orange “squishy”.
Melvin lies and tells the news station that his superpowers defeated to robo-boogers. George and Harold successfully switch Melvin’s powers back to Principal Krupp’s body and erase the memory of the newscast.
Later, at the treehouse, George discovers that Harold kept Crackers for a pet instead of returning him. The boys decide return the dinosaur without letting the machine rest. As the story comes to a close, the boys are in the time machine as something terrible happens.
Captain Underpants and the Big, Bad Battle of the Bionic Booger Boy Part 2 explores themes of anti-authority, good vs. evil, and acceptance. Once an outcast, Melvin is working together with George, Harold and Captain Underpants until he discovers that they still find him uncool and become uncooperative. Discuss with your children what appropriate and inappropriate behavior is shown throughout the book. Bring up the topic of acceptance.