Titles in this Set:

1. Captain Underpants and the Terrifying Return of Tippy Tinkletrousers (Book 9)
2. Captain Underpants and the Revolting Revenge of the Radioactive Robo-Boxers (Book 10)
3. Captain Underpants and the Tyrannical Retaliation of the Turbo Toilet 2000 (Book 11)
4. Captain Underpants and the Sensational Saga of Sir Stinks-a-Lot (Book 12)

Description:

Captain Underpants and the Terrifying Return of Tippy Tinkletrousers (Book 9)
George and Harold are behind bars for a crime they didnt commit! But just as they are settling into their new life, they are pulled from prison by a time-travelling tyrant named Tippy Tinkletrousers! Now the boys are taking a trip back in time to the carefree days of kindergarten, when the scariest thing they had to face was not evil mad scientists or alien cafeteria ladies but a sixth-grade bully named Kipper Krupp, the nephew of