Captain Underpants and the Preposterous Plight of the Purple Potty People is the eighth book in the Captain Underpants series by Dav Pilkey. It was published on August 15, 2006, two years and eleven months after the previous book. This was the last Captain Underpants book to be published for 6 years, until Captain Underpants and the Terrifying Re-Turn of Tippy Tinkletrousers was published in 2012. Plot summary George Beard, Harold Hutchins, Sulu, and Crackers have now ended up in an alternate universe in Melvin's time machine, where the whole world is the opposite of their normal world (instead of being perched up in a tree in the Cretaceous Period of the Mesozoic Era). For example, Melvin Sneedly is dimwitted and struggling to comprehend a simple children's book (which contains content considered offensive in the normal universe), the teachers are nice, the school is better, all the previous villains are good, normal citizens, and Mr. Krupp is nice and has a sense of humor (Like Captain Underpants does). George and Harold soon see evil versions of themselves and learn through one of their evil twins' comics that they had turned their Mr. Krupp into an evil supervillain named Captain Blunderpants (who acts like Mr. Krupp). Sulu and Crackers are kidnapped by Evil George and Evil Harold and are hypnotized to be evil, and then ordered to destroy George and Harold. Sulu immediately attacks, but Crackers does the opposite and saves them (due to secretly being female). George, Harold, and Crackers are able to escape to their normal dimension and head to the treehouse, unaware that Nice Mr. Krupp, Sulu, Evil George and Evil Harold came with them (due to standing too close to the machine). Evil George and Evil Harold transform Nice Mr. Krupp into Captain Blunderpants by getting water on his head. Meanwhile, George and Harold decide to head back to the other dimension to rescue and de-hypnotize Sulu and take the 3D Hypno-Ring and Extra-Strength Super Power Juice just in case. However, Mr. Beard stops George and Harold from leaving the house and forces them to come inside as it is Grandparent's Day so they can eat dinner with George's Great-Grandmother and Harold's Grandfather at George's house. While George and Harold try to explain to Mr. Beard they need to leave, George and Harold's grandparents unknowingly drink the rest of the Extra-Strength Super Power Juice while reading a