George and Harold have to figure out how to fix history in the tenth
book in this #1 New York Times bestselling series by Dav Pilkey, the
author and illustrator of Dog Man!
George and Harold have been turned into evil zombie nerds doomed to roam
a devastated, postapocalyptic planet for all eternity! Unfortunately,
the boys can't count on Captain Underpants for help because Tippy
Tinkletrousers and his time-traveling hijinks prevented George and
Harold from creating him in the first place! With Tippy having changed
the course of human history forever, George and Harold will have to
figure out a way to change it back!