When George and Harold hypnotize their principal into thinking that he is the superhero Captain Underpants, he leads them to the lair of the nefarious Dr. Diaper.

George and Harold have played a trick or two on nearly everyone at Jerome Horwitz Elementary. When their latest prank causes the school's cranky cafeteria ladies to quit, Mr. Krupp hires a trio of unusual replacements - who happen to look an awful lot like aliens! Will that curtain-caped crusader, Captain Underpants, save the day once more? Or will those outer-space cafeteria ladies have him for lunch?

George and Harold accidentally create a monster in the fifth book in this #1 New York Times bestselling series by Dav Pilkey, the author and illustrator of Dog Man!

George and Harold are always good at using their imaginations, and that drives their mean homeroom teacher, Ms. Ribble, crazy! But this time, they've come up with much more than a silly prank... With her horrendous hairdo and two rabid robots, Wedgie Woman is well on her way...