On the way back to Earth, they stop by at a Starbutts on Mars, where they discover that the store offers super power juice. They decide to take some back to Earth, and they go to the Laundromat where Captain Underpants is still held captive. They restore all his powers, and all is right with the world.
Billy and Diaper Dog return home to their parents where they all share a group hug. George and Harold end their comic, even is possible.