The five protagonists and their captor then travel to the African savannas where the boys and their pets gain the trust of some cavemen who inhabit the surrounding jungles.

The cavemen are taught English through drawings and subsequently, the boys make the world's first comic book.

After getting rid of their evil future selves by vowing never to take life seriously, they snap their fingers, turning both Mr. Krupps into Captain Underpants, and they beat up Slightly Younger Tiny Tippy, who afterward attempts to use his nuclear bomb to blow up the entire galaxy.

After that, Crackers and Sulu decide to save the entire galaxy by sending Slightly Younger Tiny Tippy and themselves back to the time before the universe existed (13.7 billion years ago).

Suddenly Melvin Sneedly, in a giant Robo-Squid, appears and captures George, Harold, Captain Underpants, and Crackers' eggs, taking them back to the past.