This is the eighth chaotic adventure in the Captain Underpants series. In this installment, fourth-graders George Beard and Harold Hutchins accidentally create a new breed of super-villain: the Purple Potty People. When they use their latest invention, the GOOFY-4, to travel to the past to stop their school principal, Mr. Krupp, from creating Captain Underpants, their time-traveling shenanigans result in the creation of two evil, toilet-themed foes who threaten to destroy the world. The boys must enlist the help of a future version of Captain Underpants (the incredibly old, boring Captain Underpants from the year 3000) to defeat the prehistoric purple people. The book is filled with Flip-O-Rama action, crude humor, and a time-travel plot that tests the limits of logic, even by Captain Underpants standards.
