The Powerpuff Girls go to Pokey Oaks Kindergarten on the first day of school, and find out it’s closed due to an earlier accident caused by Bubbles, so they get sent to an elementary school. Unfortunately, the big kids keep calling the girls babies due to their short height, so they ask the Professor to make a potion that ages them. And even worse, they consume too much of it and turn into old grannies, making them near useless against Mojo Jojo.