In their last adventure, George and Harold were turned into evil zombie nerds doomed to roam a devastated, post-apocalyptic planet for all eternity. But why didn’t the amazing Captain Underpants save the boys from this frightening fate? Because Tippy Tinkletrousers and his time-traveling high jinks prevented George and Harold from creating Captain Underpants in the first place! Now, having changed the course of human history forever, they’ll have to figure out a way to change it back. Could this be the end for Captain Underpants?